WEDNESDAY DECEMBER 11 - SNOW COVER AND CLOUDS
We're at the time of year
now when snow can turn the landscape white in a matter of minutes or
hours. That transformation complicates the interpretation of
satellite images, simply because both snow and clouds look white
To a novice, there are a few simple ways to tell the difference
between them on satellite images. First, a snowcover will end
abruptly at the edge of a water body such as a lake or a river,
but clouds won't. So a thin dark
line snaking through a field of white on a satellite image is a
river, and the white is
snow, not clouds. This technique won't work, however, if the
water bodies are frozen.
Another way to tell the difference between snow and clouds is by
playing a movie of satellite images over a few hours. The clouds
will usually move, but the snowcover won't.