Re: Rainbows in waterfalls

I found some fabulous rainbows in Upper & Lower Yosemite Fall(s) on my last trip. I know you can calculate when these will happen (based on sun location and azimuth of your view angle & such), but I was just pleasantly surprised. It would be cool to figure out the viewing windows are for these phenomena - wouldn't that be a great iPhone app?

Interestingly, none of the images I found via web searching came up with anything that matched the rainbow orientations that I encountered. Watching the Upper Yosemite Fall rainbow was spectacular through binoculars, and yes, the color saturation was increased in both images here.

From about 1400' up the Four Mile Trail at around 11:20 a.m. on March 28:


From Stoneman Meadow (adjacent to Curry Village parking lot) at about 8:20 a.m. on March 29:

Is the Four Mile Trail open all the way?

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eeek
Is the Four Mile Trail open all the way?

Not sure about today; we stopped on 3/28 at 1800' above the valley, below Union Point. Lots of snow on the trail then, and I believe it was closed at Union Point then. I was leading a group of 23 high school kids, (many in tennis shoes & shorts, one seeing snow for the first time ever), so weren't pushing to go too far.

Was that your group on the Yosemite Falls trail a couple days later?

Nope - we left in the morning on Sunday the 29th. We were at Lower Yosemite Fall on the 28th, though.

Even with the saturation enhancement those pics look surreal! I have taken some pics of Bridalveil, Nevada, and Vernal Fall with rainbows in springtime:

http://pevey.smugmug.com/gallery/7861429_DLPJB/1/#509592110_RbLcE-A-LB
http://pevey.smugmug.com/gallery/7861429_DLPJB/1/#509618359_snPCB-A-LB
http://pevey.smugmug.com/gallery/7861429_DLPJB/1/#509618862_pVSfg-A-LB

Ryan,

Nice view of the mist portion of the Mist Trail, one of the few cool spots in Yosemite during summer.

Jim

I can never resist a waterfall rainbow, no matter how many times I may have taken the same photo.

That's a great vantage point from the 4-mile trail for Yosemite falls, and all the others, especially that one of Nevada Falls' whitewater roaring to a rainbow are great.

If you're on the valley floor, the Stoneman meadow morning one gets better as April progresses...the sun hits more of the falls, and the rainbow travels down the falls as the sun goes higher. In February, you can go up to Ahwahnee meadow to get the right angle for a rainbow. Or, near the parking lot by Sentinel bridge, just walk into the meadow (February). If you head up the lower falls trail early, to the bridge, there are many rainbows throughout the year, just get there early before the crowds. There's also some good ones at Bridalveil in mid February, right from the parking lot, if the afternoon sun holds up.

If you have a polarizer, it can give the same saturation enhancement that you would do in a photo editor; just rotate it so it blocks the rainbow completely, then at about 90 degrees from there, you should see a much brighter, enhanced rainbow.

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Gary
Yosemite Photo Galleries: http://www.pbase.com/roberthouse/yo

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Sierrafan
If you have a polarizer, it can give the same saturation enhancement that you would do in a photo editor; just rotate it so it blocks the rainbow completely, then at about 90 degrees from there, you should see a much brighter, enhanced rainbow.

I was just wondering how a polarizing filter would effect a rainbow. Thanks!!

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The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan

Definitely agree with the polarizer. Helps bring out the rainbow and can give the sky a more deep vivid blue color. I pretty much leave the polarizing filter on the camera for all of my middle of the day, clear/superbright day shots. Also helps for either cutting out or enhancing the reflection on a lake or river, whichever effect you want.

The calculations for the rainbow at lower Yosemite and upper Yosemite fall are different as in one case the azimuth changes more during the time the rainbow is visible and at the other case it changes only less than a couple degrees.
The lower yosemite fall case is the more obvious and easy calculation but the one for the upper fall is more difficult to understand. Was for the upper fall the angle of the sun towards the waterfall and water fall angle important? I'm asking because the sun was perpendicular to the waterfall.

Dates and times for Moon bow this year. http://uweb.txstate.edu/~do01/moonbows2013.html

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Enny
Was for the upper fall the angle of the sun towards the waterfall and water fall angle important? I'm asking because the sun was perpendicular to the waterfall.

The position of the waterfall itself doesn't matter so much; it's the position of the spray and the sun relative to you (the observer) that determines if/when/where there'll be a rainbow.

Assuming that the sun is somewhere behind you, find (or imagine) the shadow of your head. For you to cast a shadow at all, the sun is going to have to be above the horizon so the shadow of your head will be somewhere on the ground. Call that point "P". With P as the center, draw an imaginary circle with a radius of about 42 degrees (or a diameter of about 84 degrees). If there's rain, waterfall spray, garden hose spray, or any other water droplets anywhere along that circle, you'll see a rainbow there.

If you move, the circle will move. If the sun moves (which of course it will), the circle will move. As long as you keep moving in such a way that the magic circle intersects spray, you'll continue to see the rainbow. Not responsible for clouds, ridges, trees, etc. getting in the way of the sun.

How big is 42 degrees, you ask? Imagine the last full-size rainbow you saw. That was part of a circle with a radius of 42 degrees. You could make a rainbow gauge by attaching one yardstick to the end of another at right angles. if you point the first yardstick at the shadow of your head, the 32.4-inch mark on the second yardstick will point to the magic circle where rainbows can form. These calculations not guaranteed till I've tried them out (don't anyone hold your breath).

Thank You. But the 42° rule/calculation does not apply (or maybe not the same way) on the rainbow picture of the upper fall in the morning as it does on the lower fall before noon.

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Enny

Thank You. But the 42° rule/calculation does not apply (or maybe not the same way) on the rainbow picture of the upper fall in the morning as it does on the lower fall before noon.

The 42º rule applies to all situations, all the time.

It's not a rule of Yosemite; it's a rule of physics. The 42º is due to the refraction of light through a prism (the water droplets).

.

a couple of illustrations:

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Enny
Thank You. But the 42° rule/calculation does not apply (or maybe not the same way) on the rainbow picture of the upper fall in the morning as it does on the lower fall before noon.

Most likely a different part of the magic circle is moving across (or down) each waterfall in a different direction each time.

Thanks to vdrummer for the illustrations!

Thank You.

Found one with a tiny rainbow at Nevada:



And a decent one at Vernal:

Vernal has a great one every afternoon in spring. You can also see one in the morning, looking down the Mist Trail.



Edited 1 time(s). Last edit at 05/17/2013 08:29PM by hotrod4x5.