20 Percent Chance of Snow

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Photography relies on science as much as art, and to be successful, photographers have to know a lot of things. Some of the requisite knowledge falls into the category of common sense and some is acquired through the indispensable combination of training and practice. And every once in awhile we stumble upon a nugget that can only be described as dumb luck. It was dumb luck that led me a few years ago to a website I want to share with you.

Because I’m an early riser, I’ve always wanted to know two things about my morning prospects: the weather and the approximate time when day would break. The weather is a dice roll, of course. I know, for example, that that the National Weather Service (NOAA) has issued a forecast calling for a high temperature today of 42 degrees with a low of 27 and a slight (20%) chance of snow. But I don’t believe it for a minute. A weather forecast is a guess, not a guarantee.

However, I do know exactly what time the sun will rise, and I know exactly when it will be light enough for animals (including me) to see without artificial light. Furthermore, I can, with absolute certainty, declare that on July 4th of this year in New York City the sun will set at precisely 8:30 p.m. and it will be dark enough to need a flashlight at 9:03. I can even go one step further and proclaim that there will be a Full Moon on 7-July-2009 at 5:22 a.m. Eastern Daylight Time. These are important things for photographers to know.

In fact, anyone who deals with the uncertainties of life can take comfort in the fact that some things are predictable. Sunrise and sunset are two of them. Being over your credit limit when you find a used Leica M2 marked $125 in an out-of-state pawn shop is a third.

To find out the schedule of the Sun and Moon, visit this US Navy website:

http://aa.usno.navy.mil/data/docs/RS_OneDay.php

Enter the data matching your geographic location and you’ll learn everything you need to know, including the ending time of “civil twilight.” Civil twilight is that period after the sun sets but before complete darkness when it’s still bright enough to do things outside without artificial light (i.e., you can read your watch without flicking your Bic).

From this website you will also learn that the phase of the Moon on 4-July-09 will be “waxing gibbous with 93% of the Moon's visible disk illuminated.” The word “gibbous” means that at least three quarters of the Moon will be visible and “waxing” indicates that even more of the Moon will be visible on the following night.

Photographers have to know a lot of things, even if the Moon is waxing gibbous.

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