Monday, February 11, 2019

It Was That Kind of Day: Half Dome from the Central Valley



Update: I've added an extra image at the end that shows the satellite imagery in the view from Keyes Road. 

It doesn't happen often. I usually pass the right intersection once or maybe twice a week, but the most important factor is the air quality. It's almost always poor. Dust and smoke in the summer, fog and clouds in winter. There is a spot on the floor of the Great Valley (some call it merely the Central Valley) where one can see Half Dome and the other peaks around Yosemite Valley in the Sierra Nevada.
Today was one of those days. I was going to take my customary walk on the Tuolumne River, but I could see that the air was extraordinarily clear, so I headed south to the intersection of Keyes Road and S. Hickman Road. I wasn't disappointed. I could be wrong, but I think these are the clearest views I've ever caught with a camera.
The visibility of Half Dome from the valley floor has been kind of a contentious subject. There are plenty of people who think that it isn't possible, and there are some peaks that are mistaken for Half Dome off to the north. I was actually accused of photoshopping the pictures once, which if you know me is laughable (I don't do that kind of thing very well). The trick to seeing it is to know where to look (ENE from the Keyes/Hickman Road intersection), and to realize that while Half Dome is so prominent from the floor of Yosemite Valley, it is not even 9,000 feet above sea level. The peaks behind and around Half Dome are 12,000 to 13,000 feet high. Half Dome is most definitely not on the skyline. It's in the middle foreground.
The other thing to realize is that my pictures are highly zoomed images. The image below approximates what the scene looks like from just north of the intersection. Can you pick out Half Dome in the picture below? And if you know your Sierra Nevada geography, can you name the other peaks that are visible? See how you did below!

Here, courtesy of CalTopo.com is a guide to the peaks in the picture above.

POSTSCRIPT: Thank you for all the comments. Since there is still some controversy about whether this is Half Dome, it turns out that CalTopo also offers an image overlay on the viewfinder, so I have added it below. For those who feel the mountains in back are not "tall" enough, one needs to consider the curvature of the Earth over the 40-50 mile distance of the highest peaks in the view.


53 comments:

Anonymous said...

Do you mean Hickman Rd, by Oakdale-Waterford highway? Trying to figure out the spot from Google Map.

Garry Hayes said...

Yes indeed. I've lived there so long I don't look at road signs, and forgot that Oakdale-Waterford Highway changes to Hickman Road going south. Thanks for pointing this out; I've corrected the text above.

Tracy said...

I've heard there's another spot on Warnerville road. Though I haven't found it yet.

Tammy Firch said...

I have seen it by Geer road, just north of Turlock.

Unknown said...

I find this astonishing as if not real. From Ohio and visited Yosemite 4 times and climbed/hiked half dome twice. Simply hard to believe. So no mountains higher than Half
Dome when looking west to east? Cloud rest to the upper left (behind)?

Anonymous said...

I'm sorry, but that is not Half Dome. I have repeatedly heard this myth about being able to see Half Dome from the Central Valley and it just isn't true. I don't know what that is, but it's not the famous peak. Due west of Half Dome is Glacier Point in Yosemite. GP is 7,200 feet, HD is 8,800 feet. GP alone would block out the view of all but the last 1,600 feet of the dome, and much of that would be invisible to us due to the distance and angles. And that is if GP is the only obstacle.

The images you posted seem to show your "Half Dome" as being just behind the lower foothills of the Sierra. But the real Half Dome is much further east than your photo. If you go to Yosemite, you'll notice that even inside Yosemite it can be difficult to find a clear vantage point to view Half Dome. Please do not perpetuate this myth.

--Scott Olin, Modesto CA

rmt said...

I’m having a Facebook discussion about this and I agree with you that it isn’t half dome. You can barely see half dome from inspiration point in Yosemite, yet you can see it fully from the Central Valley? And glacier point is an issue with seeing half dome from the valley. The good professor neglected to show it on his labels of landmarks.

Garry Hayes said...

Oh, I can assure you that this is Half Dome in the pictures. For one, Glacier Point is SW of Half Dome, not west. And if you look at pictures from the top of Half Dome (look at http://www.planetholloway.com/graphics/photos/edge%20of%20half%20dome%20yosemite.jpg for an example), you can see that the Merced River canyon points SWW towards Denair and Turlock. The Central Valley is visible from Half Dome, and thus Half Dome is visible from parts of the Central Valley. The angle is confirmed further by CalTopo measurements. The fact that it is difficult to see Half Dome from the valley floor is immaterial: looking at views from the top of Half Dome show that the ridge below Glacier Point blocks the view from the valley floor. But it doesn't block the view of the valley.

rmt said...

Well looking at your picture from the Central Valley, Half Dome is very prominent. Yet, even in your picture from the top of Half Dome, you can see Glacier Point and El Capitan as being just as prominent, yet in between Half Dome and the Central Valley. Half Dome at it's highest point is 8800 feet. And in your Central Valley picture, you can see the majority of Half Dome, meaning that you can see Half Dome elevations of 5000-6000 feet. However, El Capitan is about 7600 feet in elevation and Glacier Point is 7200 feet in elevation. So, if this was truly Half Dome, you wouldn't see the whole of the rock, just the top 1/4 or 1/5th of Half Dome, for both El Cap and Glacier would block the lower and middle part of the Half Dome rock. For one to see all of Half Dome, both Glacier and El Cap would have to be at about 5000-5500 feet elevation. And they are both above 7000 feet. So, you have to explain where Glacier and El Capitan are in your picture to convince me (not that I'm that important) that it is true.
I'm going to drive out there this weekend and hope for clear skies and then drive closer to see what that rock is.

Anonymous said...

I have an issue with the statement, "The peaks behind and around HalfDome are..." My point is that the tallest valley peak and nearest neighbor to HalfDome is Clouds Rest. Clouds Rest is approximately 3.5 miles away from the Dome. In photos taken from Glacier Point, Clouds Rest does not appear to rise above the height of HalfDome. As for peaks behind the Dome...MatthesCrest, Cockscomb, Vogelsang...all are an additional 10miles away and don't appear to tower above HalfDome in any photo I've seen or while I've stood upon it. Please, give names to the peaks seen behind this photo of HalfDome and then we can debate its legitimacy.

Sincerely, BAW

Garry Hayes said...

Please note that I've added the CalTopo view with satellite imagery added in, with most of the prominent peaks labeled.

rmt said...

Thanks for the CalTopo view. But again, it is missing 7200 ft Glacier Point and shows 7800 ft El Capitan as too low. I am a GIS guy and I mapped out the view line from Hickman and Keyes Rd to Half Dome. Both El Capitan and Glacier Point are right in that view line, as is the Tunnel Viewpoint, where the usual shot of Yosemite Valley and Half Dome show up (where Half Dome is mostly hidden).
In your picture and the CalTopo view, most of, 8800 foot elevation, Half Dome is shown. It is about 4000 ft elevation at the base of Half Dome, making Half Dome about 5000 ft high. So, when most of Half Dome is shown in CalTopo's view, it is safe to say that elevations of 5000-6000 ft are visible in your and CalTopo's Half Dome view. There is no way that can happen when El Cap and Glacier Point are over 7000 ft in elevation and are in between Half Dome and the Central Valley shot in the direct view line. For CalTopo's diagram to work, El Cap has to be about 5000 ft in elevation, but it is 7600 ft. And why Glacier Point is not shown is puzzling. So, it doesn't make sense given the elevation data. For this to be legitimate, the top 1/4 or 1/5 of Half Dome should be visible, if that, not the majority of the rock. That's why I'm not buying it, regardless of CalTopo's illustration.

Garry Hayes said...

You're missing something here. Half Dome does rise 5,000 feet above the floor of Yosemite Valley, but the face of Half Dome, the vertical wall, is 2,000 feet or less. That is the part that is visible in the photos. The "Diving Board" is visible at the right base of the dome, and it is at an elevation of about 7,400 feet, so these pictures show the top 1,500 feet of the face of Half Dome. Sentinel Dome is clearly visible on the right side of Half Dome, and if you check the topographic map, Glacier Point would not be visible at all because it is behind Sentinel from the angle of the Keyes Road view.

The fact is that these photos are taken looking directly at the location of Yosemite Valley from a position on the floor of the Central Valley in the one place where the orientation is correct for seeing it. The features in the pictures I took line up with those generated by the CalTopo map database. The large rock in the center of the picture is clearly a vertical cliff with same shape as Half Dome, including the "Nose" and the "Diving Board". The top of the dome is slightly indented, just like Half Dome. The tip of El Capitan and Sentinel Dome are clearly visible in their correct relation to Half Dome. And there are no other peaks or domes in the area that come close to having this appearance.


Anonymous said...

This might be able to assist. From lick observatory twice the distance as Turlock but 4200 foot elevation. https://twitter.com/LickObservatory/status/1097646752163741696

Anonymous said...

For reference purposes, Lick Observatory is 45 miles due west of Turlock (Turlock is essentially where above photo was taken). Or 120-125 as the crow flies from half dome. It sits on the summit of Mt. Hamilton, part of the Diablo Range. It sits at 4200 feet, essentially the same as the valley floor of Yosemite. Or 4600 feet below the top of half dome. Between the diablo range (which you can see part of in the lick twitter photo above-I can repost the twitter link) and yosemite valley is the Central Valley (Turlock), which sits at 62 feet above sea level or 4100 feet below Yosemite Valley. Turlock is approximately 75 miles as the crow flies from Yosemite valley/half dome.

rmt said...

The Lick Observatory picture is interesting, but it is taken at 4000 feet elevation, not 100 feet elevation. There's a big angle difference there. Looks like the same Half Dome rock formation , the you, Professor Hayes, have described as Half Dome.
Actually, I think it is you who is missing something. For how is it that when I look towards Half Dome, I can see Glacier Point from within the Yosemite Valley (from the Tunnel View turnout) and it blocks most of Half Dome, yet you cannot see Glacier Point and see most of Half Dome from the Central Valley floor. That doesn't make sense.
And your zoomed in picture shows the right side of "Half Dome" going pretty low. Sorry, but that extends well below the face of Half Dome. And El Cap should line up in front of Half Dome, as I drew a direct line from Half Dome to your photo location. El Cap is off to the left of Half Dome in your picture, whereas it should line up right in front of Half Dome from your photo location, especially at 70 mile distance away. And El Cap is 7600 feet and should only allow 1000 feet of Half Dome to show. It would look much like a picture from the Tunnel View looks, where Half Dome is not prominent, but peaking out from behind El Cap and Glacier Point. And given that El Cap is only a 1200 feet lower, there is no way the top 1500 feet of Half Dome would show. Your math may be off. But your picture shows way more than the top 1500 feet, especially on the right side and at that far away distance.

Finally, I tried a Google Earth experiment, and identified Half Dome on the map with a push pin. Then I went to your location and hovered over it at about 600m. Half Dome is barely visible. Then I went lower and the Half Dome push pin disappeared, which means it isn't visible at that height (which was about 378 m). Now Google Earth isn't the end all and be all of everything geographic, but it would show a prominent Half Dome, as your picture indicates, but it doesn't In fact, Google Earth shows that you can't see Half Dome a 1000 feet above your location. Give it a try and see what you see. And what you will find, is that there is no place in the valley where one can see Half Dome, or any Yosemite viewpoint. There are too many other mountains in the way. And given an angle from 100 feet elevation, a properly placed foothill range of 2000-3000 feet elevation can totally obscure taller mountains many miles further away, which is why I believe you cannot see any Yosemite features from the valley.
But I'm going out this weekend to see if I see what you see and try to figure out the mystery of what it is you are looking at that you identify as Half Dome.

rmt said...

And two other things. I'm comparing your picture and a picture on Google Images of Half Dome, which was shot from Glacier Point. Yosemite's Half Dome has what looks like a shoulder on the closer side of it (the right side if you are facing the wall). Your picture doesn't show that shoulder. That shoulder starts about 1/3 of the way up the wall. And that shoulder levels off a bit, while your picture looks like a continuous slope, with no leveling off.
And the back side of "Half Dome" in your picture (where the snow is) looks much wider than the Google Half Dome picture. And why that is funny is that you would think that the closer picture would look wider than the farther away picture, but it is the opposite. The back side of the rock looks narrower in the Google picture than yours. Put them next to each other and see.
Then get a picture from Tunnel View and compare it with yours. They aren't the same by any stretch of the imagination. And that is why I can't buy that your picture is Half Dome. I'd like to. But just comparing the pictures convinces me these are different, and that's besides other things that don't match up as well.

Anonymous said...

More (good) discussion regarding seeing half dome from the central valley floor: http://www.whitneyportalstore.com/forum/ubbthreads.php?ubb=showflat&Number=59083&page=0&fpart=1. Also, if you go to the Yosemite news forum site (type in “Turlock and 2010”), good pics of the Central Valley lights at night from the half dome diving board.

Anonymous said...

I do not have a dog in this fight—simply a curious observer from Ohio. I have been following the Turlock/Half Dome question since reading about it in the Yosemite News Forum years ago. I found it hard to believe, did not seem possible. But perhaps a bit of Fox Mulder in me and I wanted to believe. Initially, thought there was not a possibility of seeing Half Dome from the West—thinking the view had to be blocked by other mountains (I likely was too focused on thinking of seeing from the East, which is not possible).

Assuming one could see it from the West, then issues of curvature of the earth and lens distortion came into consideration—in part for why Half Dome is so prevalent over other notable sites (Capitan, Glacier Point, etc.). The recent photo from Lick Observatory (assuming not photoshopped and nothing indicates it is), allows me to remove some of my biases.
First, one can see Half Dome from the West with no obstruction from other mountains/ranges. The shot was taken from an elevation of 4000 feet but certainly one could drop down in elevation and continue to view Half Dome if not obstructed by the Diablo Range. How low from a distance of 120 miles, unclear. 3000 feet? 2000 feet? 100 feet?

Also, the shot is similar to photos/video taken from Turlock/Central Valley, including the photo in this blog. Half Dome is quite dominant (in particular the face—which appears to be elongated). El Cap does appear to me much lower (on the left) and Glacier Point is not seen. You can especially notice the similarity if you view the photos side by side and blow them up—I can forward if it would be helpful.

With that said, I too remain uncertain in my judgment. Preponderance of the evidence (more than 50%), yes. Clear and convincing or beyond a reasonable doubt, not quite there. I guess I would have to see with my own eyes (telescope) or perhaps MythBusters could do a show on it.

Anonymous said...

The conversation is getting pretty silly. I appreciate the work CalTopo does. However, an elevation profile is not a realistic perspective, even when overlaid with satellite imagery and labels. That is why the objects in your photograph are what need to be identified to provide the right impression of height, width, and position in relation to the object you identify as Halfdome.
Failing to do that...how about a photogrammetry approach? You have provided the approximate location of where the photo was taken. We can closely approximate the distance to Halfdome. With some google earth mensuration, we can calculate the foreground builds height, width, and length. So provide the Focal Length of the lens and the sensor size and we'll determine the size of the (Halfdome)object in your photograph.

Nephi Polder said...

I thought I’d attack this with trigonometry. Using https://www.mapdevelopers.com/distance_finder.php I measured the distance from the middle of Turlock to HD as 391371 feet and the distance from Turlock to the highest point I found between on the approximate sightline from Turlock to HD (a hill at 3400 feet [37.653165, -119.929321]) at 272318 feet (the hundreds of feet will vary widely if you try to repeat this on the map-consider them non-significant digits but I used them in the calculations). Using the arctangent function (opposite = height and adacent = distance) then arctan of Turlock to HD is 8800 feet over 391371 feet is an angle of 1.28 degrees. The arctan of Turlock to hill is 3400 feet over 272318 feet for an angle of 0.715 degrees. I assumed Turlock was at sea level for simplicity. So from Turlock the top of HD would appear higher than what I considered the highest hill that could obscure its view.

Unknown said...

Highway 99, take the South Ave. Exit and from that overpass you can see Half Dome on clear days looking east. Enjoy.

David Hansen said...

I'm thinking that half dome is ENE from Keyes and Hickman road. I stood on the spot where you took the picture and although I didn't have a compass, the direction is closer to East than North. Thanks for posting. It was fun to go look.

Garry Hayes said...

You are absolutely right, I didn't proofread as carefully as I should have. The dome is indeed just a few degrees north of due east. I will correct the text. Thanks!

Ken Murray said...

Guys, this has been debated by people with far more experience and GIS wizardry than anyone here. For years.

But for all the pseudo-scientific junk being thrown out, it is just like the math that demonstrates, beyond a doubt, that bees cannot fly.

rmt says he's driving out there to see for himself. Perhaps he won't trip over the official sign placed out there by the National Park Service, at one of the viewing points?

But most importantly, I've read too many posts by deathbound skeptics, who went out there and took their own photos and videos, posted them, and gracefully had to eat a lot of crow. Be as certain as you want, but watch a bee sometime.

Ken Murray said...

For example, check this out:

http://www.whitneyzone.com/wz/ubbthreads.php/topics/8840/Half_Dome_From_Turlock-The_Fin

Ken Murray said...

http://hoaxes.org/weblog/comments/can_you_see_half_dome_from_the_central_valley

Nephi Polder said...

Ken, I think this is an excellent forum for people to debate whether or not they rely on pseudo-scientific junk as you call it. At least people walk away either believing it's visible or not. I'm more concerned if people vaccinate their kids than if they believe HD is visible. But let's be open to discussion. At least there is a discussion.

Nephi Polder said...

I've been on top of half dome twice when I was young and I have a degree in science and I love geography and now love geology, in no small part to the posts I read here, but I was skeptical when the first photos of HD from Turlock were discussed years ago.et people work through the evidence without slamming them for their disbelief.

Nephi Polder said...

And another comment, I think viewers aren't used to the type of zoomed photos shown here. My best analogy is the Hubble deep field images. They show lots of huge galaxies that appear right next to each other when they are many many light years apart. The zoomed photos of half dome also introduce that kind of disorientation, in my opinion.

Garry Hayes said...

About the disorientation. When I do these kinds of posts I try to include a picture at normal scale as I did in this post.

Nephi Polder said...

Thanks Garry. I see your normal scale picture and I think there's still some kind of zoom involved. It's just my eye and disbelief but I don't live in the Great Valley. So I welcome others to have disbelief and work with it. I am convinced HD and El Cap and all the beautiful high SierraSierra are visible from a few privileged vantage points. The snowfall at 1500 feet and clear air in SoCal have given me sights that I couldn't believe at first glance. Seeing isn't always believing but let's have a discussion on when it can be.

Anonymous said...

rmt was willing to take the time and drive to the location. He captured photos of HD. Providing me his camera info and lens info(exif). The math suggested the object appearing to have the profile of HD an 8800ft' object at a distance at 67 miles. Unfortunately, with the known ht and distance using the rmt photo the HD object would need to be 138 miles distance from the location on Hickman. However, with speculation on the size of the HD object in rmt photo being 3800 to 4200ft...the math greatly improved to something more realistic. Placing the object distance 48miles from Hickman rd.in the region of Sweetwater ridge, Blackmountain. Bearing 76.1* Still I would appreciate similar exif data regarding your photos.

Garry Hayes said...

Did you account for the curvature of the Earth at 70 miles? More than 3,000 feet would be hidden beneath the horizon.

In any case, I've taken pictures of Half Dome at many different times, and when the sun is right you can make out the light and dark parts of the face of the dome. For instance, this post from last year: https://geotripper.blogspot.com/2018/03/yosemites-half-dome-makes-appearancein.html. I've also found other angles, including from Hopeton: https://geotripper.blogspot.com/2014/11/seeing-half-dome-from-californias-great.html. From that angle the top of El Capitan and Cloud's Rest are more clearly delineated.

If you go to the links in the earlier discussion, you can find a number of shots from the top of Half Dome, and they clearly show the Central Valley, especially shots taken at night that show the city lights. The upper part of Half Dome is visible from the valley floor in the vicinity of Denair and Turlock.

And finally in such arguments, no one has ever provided an alternative explanation, i.e. a dome somewhere in the foothills that is shaped like Half Dome, is flanked by other features that look like Cloud's Rest, El Capitan, and Sentinel Dome, but is not actually Half Dome.

Ray Prock said...

Here are a few tips to help not raise suspicion of the property owners near this intersection. There is a group of us who are very diligent about suspicious vehicles in the area. Unfortunately the less than stellar members of society are creating heightened awareness that affects everyone.

Please obey any signs you encounter on property lines and not venture into private property.

There are several areas along the roadways that are safe enough to pull off and get a view of this unique sight.

If you do need to enter private property for any reason head to one of the houses or farm offices to try to find the property owner.

We don't want to hinder those of you who are trying to see something truly special so please help is out.

Thanks!

Joan said...

Check out this article about GIS viewshed analysis: http://caltopo.blogspot.com/2013/05/viewshed-analysis.html

Scroll about halfway down to see the viewshed of Half Dome. There is way more area in the central valley that half dome is viewable from than from Yosemite itself. It also shows how it's viewable from the Lick observatory.

I agree that it seems almost crazy that it could be viewed from the Valley, but it seems to be possible. Btw, I grew up in the Valley and go to Yosemite multiple times a year and have hiked to the top of half dome, so I'm pretty familiar with the area (and GIS is my job).

I don't think it's appropriate to compare views from Yosemite Valley or places like tunnel view to those in the Central Valley because they are so much closer to Half Dome (and tunnel view is also more north than Turlock, so the viewing angle is different). These closer viewing areas can be impeded by things (even things lower in elevation than half dome) but between the viewpoint and Half Dome. Currently I live at the base of some pretty large mountains (they rise extremely quickly, no foothills really) and peaks that are much taller than anything around them are blocked from view at my home from landforms much much lower in elevation than the peaks. If you drive further away, somewhere flat, you can clearly see the peaks.

I've scoped out some good spots in the valley that I think half dome should be visible from but unfortunately whenever I'm visiting I either don't think about it, the air is way too crappy or there are clouds covering the mountains on the rare clear days. I'm currently planning a summer trip with a possible summit of half dome. Maybe the air will be clearer than my last trip and I will be able to see the Central Valley! Joan

Joann said...

Or this photo from the Lick Observatory just a few days ago! Note the second photo with a few landmarks labeled. Looks pretty much like the photos in this post but with a few clouds.
https://twitter.com/LickObservatory/status/1097646752163741696
Joann

rmt said...

There seems to be some conflict between the claim that Half Dome can only be viewed at a certain spot in the valley as it lines up with Yosemite Valley and Joan's point that there is way more area in the central valley that Half Dome is visible with and CalTopo's map showing all the various locations that Half Dome can be seen from. Someone is not correct here, for if Half Dome can be seen from many different vantage points in the Central Valley, then the narrative that the reason we can see Half Dome from the Central Valley is because of that line of sight down Yosemite Valley is only visible in one specific area is not correct. Both can't be true. There is either an exclusive view or not.

Garry Hayes said...

No one is claiming there is a single spot in the valley. I've posted views in the past from sites several miles apart. The area of the valley from which HD is visible is limited, however, as shown by views from the summit of HD showing only a portion of the valley floor (follow the links in the comments to find the pictures). The various views show more or less of the dome. Some spots are better than others.

rmt said...

And I've gone to this area to view "Half Dome" and as a skeptic, would like to put to rest the "photoshop" narrative. This rock, as shown in these pictures by Professor Hayes, does exist and is not photoshopped. I have pictures of it.
I went on Thursday (2/21) just after the sun set, with somewhat clear views and Saturday (2/23), with crappy clarity. I am taking GPS points as to the various places I've gone to and will use a triangulation method of comparing various points where I stood along with easily identified landmarks in photos to determine exactly where this "Half Dome" is.
Similarly, I would like the good professor to provide us with his GPS points of where he has taken his pictures so that we can determine the bearing of the line of sight between his location and Half Dome.

I have done the same with the 2009 photo site (Hall Rd .65 miles S. of Keyes Rd). I took photos of "Half Dome" at this site on 2/21, when the air was clear, but the sun had just set. I took GPS points on where I stood and was able to identify a barn in the picture and to get a Google Map GPS reading on it. At first look, the bearings different by a degree, leading to an 8200 ft difference in location at 68 miles. Might be significant.
I have discovered a number of good locations to view the mountains in and around that specific area and when I have a good viewing day, will take pictures there of Half Dome and try to figure out bearings from those various locations to see if they all line up on Half Dome, where all these bearing lines meet. I didn't see Half dome on 2/23, with the air quality and lighting not so good. Will try again in the future.

rmt said...

Nephi.
I appreciate your calculations of line of sight. However, using 8800 feet is the not the right way to go at it, for there is much more of the rock visible than the tip top of it. It looks like at least 2000-3000 feet of that rock is visible in these central valley photos. So, instead of using 8800 feet, you should try various exercises using 7000, 6000, 5500 and 5000 foot elevations to see if anything is blocking the middle towards bottom of the rock, as that is clearly visible in these pictures.

Anonymous said...

I absolutely agree with Ray Prock. I too live in amongst an agricultural community. And I'mm aware of the recent and persistent thevory occurring to agriculture equipment(copper wire, bee hives...) And roadway safety is a absolute must! A 10 acre orchard doesn't seem like someones backyard to City folk. Yet most farmers know more about the condition of that rear 660ft, than most know about their own front door.
In my prior comment my use of the word speculation was purposeful. While I'm intimately familiar with Yosemite Valley, extending as far North as Crabtree trail head and eastward to Sunrise. The areas South are not familiar to me. I've only traveled the 140hwy less than handful of times. I say this because having used the "Redbarn" in rmt photo, the tree visible off Montpelier east right-of-way in both rmt and your photo as a means to determine a bearing for the sightline. These sightlines extending towards Half-dome lead me to an intersection with Sweetwater ridge, midpines area. I had to ponder the idea that a snow covered Sweetwater ridge in a photo, could appear similar to a snow covered Clouds Rest. Using the height of Sweetwater in the focal length calculation resulted in distance accuracy confirmable in mensuration. And for me explains the additional observable features in the background of the photographs. Having stood atop Half-dome more than a dozen times, and numerous more time on both El Capitian the Upperfalls. And Cloudsrest was a weekly day hike for me during an extensive period in my life. Seeing features in the photographs towering above in the background above those you say are Cloudsrest and Halfdome is difficult for me to...wrap my head around.
As to the question of another object in the sightlines also appearing similar to Half-dome. I can only comment that a rainbow in the dark was only a lyric in a song, until I saw one for myself. And the appearance is more common than I first had imagined.

The curvature calculations I used: https://dizzib.github.io/earth/curve-calc/?d0=67&h0=5&unit=imperial
However, we must assume the realative value of both the observation height and object viewed as an elevation above sea level. Regardless of there individual geography position.

Lastly, I've no desires to disapprove or prove. Rather, I'm interested in exercising my limited knowledge and the tools at my disposal to better understand this fascinating subject. And that those other eyes following these exchanges will refrain from disparaging dialogue regarding beliefs.
The topic of whether one believes or disbelieves Half-dome is visible in the photograph, from Hickman rd. or the moon will not further understanding.

rmt said...

Professor Hayes,
You are basically claiming there is a single spot, although it is specific narrow sight line (as you state "The area of the valley from which HD is visible is limited"). Have you seen CalTopo's map which shows a wide swaths of the Central Valley and beyond as being able to see Half Dome? I'm assuming you have, given that you have used them as a reference to point out Half Dome to us. It is your claim and CalTopo's map that are at conflict with each other. This is what I'd like cleared up.
I will do my own research to see if I can see Half Dome from Oakdale or further North or further South given the right air conditions. Given it's prominence in your picture from the valley floor, it seems that it should be visible in many different bearings from Half Dome. That is my hypothesis and seems to be CalTopo's claim as well.


Garry Hayes said...

You are splitting hairs now. I not only accept CalTopo's data, I've been promoting it. But be aware that many of the sight lines will reveal only a small portion of the summit of Half Dome. The spot I've talked about at Keyes Road and the Hall Road locality show more of the dome than most other sites. As you have apparently found with your own observations. I wish you many clear days for your explorations. Take powerful binoculars or a camera with a really good zoom lens.

rmt said...

I don't think I'm splitting hairs as CalTopo doesn't make the claim that the majority of those views are only the top of Half Dome, a point to which I don't fully disagree with as some of the locations seem a bit outrageous. However, this is your assumption of their map.
That map, described as line-of-sight locations between the central valley and summit of Half Dome, extend from Tracy to the Coalinga area, a wide wide swath. And surely some of those views would be the top only, but I'm guessing that they think many of those views outside your line of sight "red zone" are locations that can see "Half Dome" the way your posted pictures depict. Otherwise, what's the point of this exercise, originally?
Their point in the article showing this map is to verify that Turlock is within their calculated line of sight red zone for Half Dome.
So, without a disclaimer from them that all but the Turlock zone is just the tip of Half Dome views, I don't think you or anyone else can make that assumption. If CalTopo comes out and says as much, then I'm on board with that and we can move on.


rmt said...

So I took a picture and found a picture. Here's the link:
https://www.flickr.com/gp/97195299@N08/9ui1sH
You will see the one I took on 2/21/19, which appears to be the same rock that you are referring to in your blogposts. This is the evidence I have that you, or anyone else, did not photoshop it.
But you will notice the second picture, which is from Google Maps street view from Half Dome View Point along Big Oak Flat Rd approaching Yosemite (looking East). Half Dome is tiny in this picture and is not the tallest rock in this view. El Capitan on the left looks taller and Glacier Point, which is barely peaking out from another ridge, on the right, looks to be about the same height as Half Dome. I found this spot, because it lines up perfectly, and I mean perfectly, with the bearing from Half Dome to the 2009 photo location. This view point sits at 4700 feet elevation.
Somehow for your claim to be true, the rock at 68 miles away cannot be as big as it is. And as I have claimed over and over again, the surrounding topography around Half Dome is not the same as in your photo. Putting these 2 pictures side by side makes it pretty obvious. And remember, this is at the same bearing as the 2009 photo (a line drawn between .65 miles South of Keyes Rd on Hall Rd to Half Dome runs right through this view point). So a view from Hall Rd would have to somehow get through this viewpoint and show the same topography as is shown from the viewpoint. Now you have taken pictures from a different point. The latitude and longitude of that location would be appreciated to see if there is any different bearing. I'm guessing it is different, but not by much - not so much that it would not also run over or very close to this Half Dome View Point. I think this comparison seals the deal. They are not the same thing. Now, my problem is that I have to figure out what that rock is that we can see from the valley. But it is clear, it is not Half Dome.
And I also have some problems with the CalTopo range, as I've been plotting points from the mountain range on a map, and there seem to be some points not consistent with where those points of interest actually are. I have more research to do on that still, but at first glance, there seem to be some problems.

Garry Hayes said...

Good luck on your quest. Please report when you've found the rock you are looking for.

Joann said...

Hi rmt, half dome does look pretty big in all the photos from the central valley. I've wondered about that and it does seem odd. But it is pretty big and would stand out with it's flat face (and it's angled nicely). It looks like your photo, the third photo from the top in the post and the view from Big Oak Flat all have the same angle of the rock face. This seems to help the case that it's all the same feature/rock face. (The third photo looks like it was taken just one road to the west from your photo on Hall rd. You can see the same buildings on google street view as in the third photo, so the bearing should be basically the same). Also, comparing what you can see and how big things are to half dome from the photo taken at big oak flat road vs. the centrally valley, probably isn't completely appropriate (even if they are on the same bearing). I'll try and explain why just with my currently tired mind and eyeballing places on google maps. At the big oak flat view point, half dome is twice as far away as el capitan, so el cap would look waaaay bigger and taller. I assume el cap is bigger (right?) but because of the perspective and relative distances to the viewpoint, it seems that the size and elevation of el cap are exaggerated when viewed from the big oaks road viewpoint. I know there's a better and more scientific explanation but I can't quite think of it right now. Maybe someone else can?

Also, even though they are on the same bearing, the Turlock location is farther south, at a much lower elevation and there is quite a bit of difference in distance between the two view points and half dome (10ish miles vs 68ish?). So, it doesn't seem like the exact same topography/features would be visible. Many, but not all, should be visible but they would look different from the two locations due to perspective, distance and extra topography/landforms visible from the Valley.

All that being said, sometimes I look at one of these photos and think 'no way!" and other times it seems obvious it's half dome. Either way I'm jealous of those of you who can run out there on a particularly clear day and take a look. And if it isn't half dome, what the heck is it? (seriously. not being sarcastic)

None of that is what I wanted point out. I just wanted to clarify that I think the the viewshed analysis was done from a single point (probably at the top of half dome). So only the middle of the red area on the viewshed map would have the broadest and best view of the face of half dome. Turlock happens to be in the sweet spot, right in the middle. I'd be curious if the analysis could be re-ran with a polygon covering the majority of the vertical area of the face of half dome as opposed to a single point on the ground. Must be a 3D way to do it but it's beyond what I know how to do. But I bet the red area on the viewshed map would much much smaller!

Garry Hayes said...

Thanks Joann. I think you caught most of the salient points.

Joann said...

One more thing and then I'm finished, lol. I think the face of half dome (the flat portion) is about 2,000 feet! That's huge! The whole thing rises 4,700 feet above yosemite valley floor and 8,700ish feet total.

rmt said...

Joann,
I appreciate the time and effort you put into your reply. However, one thing needs to be made clear. The view of Half Dome from Big Oak Flat Rd lies along the bearing from the 2009 photo to Half Dome. This is big. For that is what Half Dome would look like at any distance, albeit further away it will look much smaller and at a lower elevation, it will disappear behind the features that are hiding it now. So, the view from Big Oak Flat is as good as it is going to get at that bearing.
Let's look at this example.
If you look at the New York City skyline from the top of the Statue of Liberty, you will see the Empire State Building standing out. But you may only see the top 40 or so stories (not sure if that's the number but bear with me). Now if you went to the base of the Statue of Liberty and looked at the Empire State Building, you would still see it, but you would see the top 20 stories or so, as other buildings that previously may not have blocked it, are now blocking it. So, lets go to New Jersey, further away, but in the same bearing. You will probably see a few more stories (maybe 25) because some of the close up buildings will not be blocking it. However, the same buildings around the Empire State Building (ESB) will still be around it. That skyline that is near the ESB will never change. And if you move 30 miles away along the same bearing, you will still see the same skyline. However, you will never see the top 40 stories (the view from the top of the Statue of Liberty) and the ESB will be getting smaller, not larger, the further away you are.

Same with Half Dome. That skyline, that shows El Cap and Glacier Point making a V in which Half Dome sits in the middle will not change at that same bearing. And should one go lower in elevation, you would lose the view of Half Dome completely. And if you go further away, you will also see the Big Oak Flat viewpoint as well and Half Dome and El Cap and Glacier will all get smaller, not larger, and El Cap and Glacier will not disappear while Half Dome remains. If El Cap and Glacier disappear, Half Dome also will disappear. At that bearing, this is the view of Half Dome regardless of where you stand (unless you go higher in elevation, but that's not the direction we are moving in).

So, given the picture of Half Dome from Big Oak Flat Rd and the picture of "Half Dome" from the valley, it is more than obvious that they aren't the same thing, no matter how you spin it.

rmt said...

Professor Hayes,
We both have a problem. I've admitted and you concur that I have to find what that rock is, if not Half Dome. However, you also have a problem. You have to find El Capitan and Glacier Point that surround Half Dome, like they do in the Big Oak Flat Rd picture. At this point, it is a hypothesis that the valley picture is Half Dome. You have to prove it to be true. And just by saying it is Half Dome and having others agree with you, giving you a consensus, is not proof.
I'm giving you alternative, objective, and unbiased evidence that it isn't Half Dome. I've also been open about where I took the picture (same as 2009 picture), and I can give you the lat long if interested (use an app on your phone to figure it out), so that a bearing could be created between the 2 points. I've asked you for the same, and I hope that it is something you will eventually supply so that we can develop a bearing for your personal picture.
So given this alternative evidence that seems to contradict your hypothesis, it is incumbent on you, a professor, to be able to argue for or against it and to apply this evidence to your hypothesis. So I look forward to that discussion. And as I replied to Joann, this is the view of Half Dome from this bearing, regardless of distance from Half Dome - of course further away distance means a smaller Half Dome, not larger. And a lower elevation will lead to Half Dome lowering within the V shape that El Cap and Glacier Point create. Half Dome will not remain while Glacier and El Cap disappear the further away you go. That view either remains the same or disappears entirely if other features block it. But it is silly to think that Half Dome will become more prominent and the other 2 features get less prominent and disappear if you go further away and lower in elevation. If you go higher in elevation, that would be true, but we aren't going in that direction.
Anyways, it seems that you also have a problem, finding El Cap and Glacier in your view. I look forward to your discussion about this. And I will continue to work on my problem.

Garry Hayes said...

You are welcome to continue your quest to prove this is not Half Dome, but you will not find a candidate in the Sierra foothills that comes even close, and I have other pressing issues to deal with. Your own picture (https://www.flickr.com/gp/97195299@N08/9ui1sH) provides some of the best evidence that we are looking at Half Dome. You took the picture when clouds obscured the peaks behind Half Dome, leaving three main features prominent: Cloud's Rest on the left, Half Dome, and Sentinel Dome on the right. El Capitan is present in front of Half Dome and slightly to the left but it is 1,200-1,800 feet shorter than HD, so it is barely visible over the other ridges in front. One point that bothers me is that you keep mentioning Glacier Point. It is simply not visible from anywhere to the west. It's at 7,200 feet and entirely behind Sentinel Dome (8,122 feet). You will never see Glacier Point in any of these pictures. Zooming in on Half Dome in your picture, you can see the black streak of mineral deposits down the middle of the face which separates the lighter colored parts of Half Dome. Those features were hidden in the shadows of my latest pictures, but have appeared in earlier pictures that I've posted (example: https://geotripper.blogspot.com/2018/03/yosemites-half-dome-makes-appearancein.html

I appreciate the effort you have put into trying to understand the spatial relationships that allow Half Dome to be seen from the valley floor, but you have ignored one of the easiest proofs that Half Dome can be seen from the valley floor: the valley floor is visible from Half Dome. There are numerous pictures that show this, for instance the one at https://www.flickr.com/photos/sheldonneill/6746503597/in/photostream/.

I will leave this discussion open for now, and you are welcome to comment when you find the mountain you seek.