MOONBOW PREDICTIONS FOR 2011
UPPER YOSEMITE FALL

image001.jpg     image003.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 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

 

July 12

(Tues)

9:25pm

(Tues)

to

10:00pm

(Tues)

95%

waxing

 

July 13

(Wed)

10:05pm

(Wed)

to

10:40pm

(Wed)

99%

waxing

 

July 14

(Thurs)

10:10pm

(Thurs)

to

11:05pm

(Thurs)

100%

 

 

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/