Don Olson
Russell Doescher,
Roger Sinnott (Sky & Telescope) Moonbow May
11, 2006
Department of Physics
Kellie Beicker, Ashley Ralph, and Don Olson
Photo by Robert Stavers
Texas State
University
at the Lower Yosemite Fall Viewing
Area
www.galleriehare.com
MOONBOW PREDICTIONS FOR 2011
LOWER YOSEMITE FALL
based on the methods described in this article:
"Moonbows over Yosemite," Sky & Telescope, May 2007
related story:
http://www.txstate.edu/news/news_releases/news_archive/2007/04/Moonbow041207.html
visual
observers generally report that moonbows appear "white,"
"gray," or "silvery"
but
time-exposure photographs reveal the full palette of colors
MOONBOW PREDICTIONS FOR 2011
OBSERVING LOCATION:
VIEWING AREA, TERRACE AT THE WEST END OF THE BRIDGE
NEAR THE BASE OF
|
DATE IN 2011 |
TIMES (PACIFIC DAYLIGHT TIME) |
LUNAR PHASE |
REMARKS |
|
April 16 (Sat) |
8:15pm (Sat) to 10:20pm (Sat) |
99% waxing |
moonbow becomes visible when sky gets dark enough at about 8:15pm |
|
April 17 (Sun) |
9:30pm (Sun) to 11:50pm (Sun) |
100% |
VERY BRIGHT MOONBOW (full Moon occurs at 7:44pm PDT on April 17) |
|
night of April 18-19 (Mon-Tues) |
11:30pm (Mon) to 1:15am (Tues) |
98% waning |
|
|
night of April 19-20 (Tues-Wed) |
12:55am (Wed) to 2:30am (Wed) |
93% waning |
|
|
May 14 (Sat) |
8:45pm (Sat) to 9:20pm (Sat) |
93% waxing |
moonbow becomes visible when sky gets dark enough at about 8:45pm |
|
May 15 (Sun) |
8:50pm (Sun) to 10:45pm (Sun) |
98% waxing |
moonbow becomes visible when sky gets dark enough at about 8:50pm |
|
night of May 16-17 (Mon-Tues) |
10:25pm (Mon) to 12:05am (Tues) |
100% |
VERY BRIGHT MOONBOW (full Moon occurs at 4:09am PDT on May 17) |
|
night of May 17-18 (Tues-Wed) |
11:40pm (Tues) to 1:15am (Wed) |
99% waning |
moonbow appears just as Moon clears south rim of valley |
|
night of May 18-19 (Wed-Thurs) |
12:45am (Thurs) to 2:10am (Thurs) |
96% waning |
moonbow appears just as Moon clears south rim of valley |
|
June 13 (Mon) |
9:20pm (Mon) to 10:55pm (Mon) |
97% waxing |
moonbow appears just as Moon clears south rim of valley |
|
June 14 (Tues) |
10:30pm (Tues) to 11:55pm (Tues) |
100% |
moonbow appears just as Moon clears south rim of valley |
|
night of June 15-16 (Wed-Thurs) |
11:25pm (Wed) to 12:55am (Thurs) |
100% |
moonbow appears just as Moon clears south rim of valley |
|
night of June 16-17 (Thurs-Fri) |
12:05am (Fri) to 1:40am (Fri) |
98% waning |
|
CONDITIONS REQUIRED TO OBSERVE A MOONBOW IN
for observers at the viewing area, the terrace just west of the bridge near the
base of Lower Yosemite Fall
1. bright moonlight (nearly-full Moon)
2. Moon risen above the south rim of the valley (so moonlight can strike
Lower Yosemite Fall)
3. sufficient mist and spray (during snowmelt runoff season: April, May,
June, sometimes July)
4. clear skies
5. dark skies (Sun more than 9 degrees below the horizon)
6. geometry (the angle between the “anti-lunar direction” [observer’s
shadow cast by the moonlight] and the
direction toward the base of Lower Yosemite Fall must
be near the “rainbow angle” of 42 degrees)
NOTE
If the snowmelt runoff is unusually strong, then moonbows could appear earlier
and last longer than the predicted times.
If the snowmelt runoff is unusually weak, then moonbows would be visible for
shorter intervals than the predicted times.
NOTE
Feedback from photographers / observers regarding the accuracy of our
predictions is welcomed
by Don Olson at
dolson@txstate.edu
LINKS
Texas State University Honors Program
http://www.txstate.edu/honors/
Sky & Telescope
http://www.skyandtelescope.com/
Don Olson, Physics Department, Texas State University
http://uweb.txstate.edu/~do01/
Marilynn Olson, English Department, Texas State University
http://www.english.txstate.edu/people-contacts/faculty/olson.html
Christopher Olson, JD, Hawaii Lawyer, Oahu Lawyer, Oahu,
Hawaii
http://hawaiiattorneyonline.com/