MOONBOW PREDICTIONS FOR 2011
UPPER YOSEMITE FALL
Photo by Brent
Gilstrap
Google Earth
http://groundhog.smugmug.com/Nature
based
on the methods described in this article:
"Moonbows over Yosemite," Sky & Telescope, May 2007
related story with photo gallery:
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
UPPER YOSEMITE FALL
TIMES CALCULATED FOR COOK’S MEADOW
OBSERVING LOCATION:
PARKING LOT JUST NORTH OF SENTINEL BRIDGE
|
DATE IN 2011 |
TIMES (PACIFIC DAYLIGHT TIME) |
LUNAR PHASE |
REMARKS |
|
night of April 18-19 (Mon-Tues) |
11:05pm (Mon) to 12:10am (Tues) |
98% waning |
|
|
night of April 19-20 (Tues-Wed) |
1:00am (Wed) to 1:40am (Wed) |
93% waning |
|
|
May 15 (Sun) |
8:50pm (Sun) to 9:15pm (Sun) |
98% waxing |
moonbow becomes visible when sky gets dark enough at about 8:50pm |
|
May 16 (Mon) |
10:20pm (Mon) to 11:10pm (Mon) |
100% |
VERY BRIGHT MOONBOW (full Moon occurs at 4:09am PDT on May 17) |
|
night of May 17-18 (Tues-Wed) |
11:50pm (Tues) to 12:30am (Wed) |
99% waning |
|
|
night of May 18-19 (Wed-Thurs) |
12:55am (Thurs) to 1:30am (Thurs) |
96% waning |
|
|
June 13 (Mon) |
9:25pm (Mon) to 10:05pm (Mon) |
97% waxing |
|
|
June 14 (Tues) |
10:40pm (Tues) to 11:15pm (Tues) |
100% |
|
|
night of June 15-16 (Wed-Thurs) |
11:30pm (Wed) to 12:10am (Thurs) |
100% |
|
|
night of June 16-17 (Thurs-Fri) |
11:55pm (Thurs) to 1:40am (Fri) |
98% waning |
|
CONDITIONS
REQUIRED TO OBSERVE A MOONBOW IN
1. bright moonlight (nearly-full Moon)
2. Moon risen above the south rim of the valley (so moonlight can strike
Upper 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 Upper 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/