MOONBOW PREDICTIONS FOR 2010
UPPER YOSEMITE FALL

Brent Gilstrap moonbow 425x471.jpg Sentinel Bridge parking lot Google Earth.jpg
                       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 2010
UPPER YOSEMITE FALL

 

TIMES CALCULATED FOR COOK’S MEADOW

OBSERVING LOCATION:  PARKING LOT JUST NORTH OF SENTINEL BRIDGE

  

DATE
IN
2010

TIMES
(PACIFIC
DAYLIGHT
TIME)

LUNAR
PHASE
 

REMARKS

April 27
(Tues)

8:30pm
(Tues)
to
10:05pm
(Tues)

100%

moonbow is already in progress when sky gets dark enough at about 8:30pm

bright moonbow
(full Moon occurs at 5:18am PDT on April 28)

night of
April 28-29
(Wed-Thurs)

11:15pm
(Wed)
to
12:05am
(Thurs)

99%
waning

 

night of
April 29-30
(Thurs-Fri)

12:50am
(Fri)
to
1:25am
(Fri)

96%
waning

 

May 25
(Tues)

9:00pm
(Tues)
to
9:30pm
(Tues)

96%
waxing

moonbow becomes visible when sky gets dark enough at about 9:00pm

May 26
(Wed)

10:25pm
(Wed)
to
11:05pm
(Wed)

99%
waxing

 

night of
May 27-28
(Thurs-Fri)

11:40pm
(Thurs)
to
12:15am
(Fri)

100%

 
 

night of
May 28-29
(Fri-Sat)

12:35am
(Sat)
to
1:10am
(Sat)

98%
waning

 

night of
May 29-30
(Sat-Sun)

1:15am
(Sun)
to
1:50am
(Sun)

94%
waning

 

June 23
(Wed)

9:30pm
(Wed)
to
10:00pm
(Wed)

95%
waxing

(brightness and duration depend on snow season and snowmelt runoff)

June 24
(Thurs)

10:30pm
(Thurs)
to
11:00pm
(Thurs)

98%
waxing

(brightness and duration depend on snow season and snowmelt runoff)

June 25
(Fri)

11:15pm
(Fri)
to
11:50pm
(Fri)

100%

possible bright moonbow
(depending on snowmelt runoff)
(partial lunar eclipse begins at 3:17am PDT
  on June 26)

night of
June 26-27
(Sat-Sun)

11:45pm
(Sat)
to
12:20am
(Sun)

99%
waning

(brightness and duration depend on snow season and snowmelt runoff)

night of
June 27-28
(Sun-Mon)

11:35pm
(Sun)
to
12:35am
(Mon)

97%
waning

(brightness and duration depend on snow season and snowmelt runoff)

 
CONDITIONS REQUIRED TO OBSERVE A MOONBOW IN UPPER YOSEMITE FALL 
 
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/