Color Your World
Color the picture by clicking on a color swatch at the bottom of the image then click on the image where you want to apply that color. Color off-line by downloading and printing the pdf version.
In order for precipitation to form, particularly over a large area, several ingredients are necessary. First there must be a source of moisture. The primary moisture sources in the U.S. are the Atlantic and Pacific Oceans as well as the Gulf of Mexico. Winds around high and low pressure systems (a subject of another lesson) transport this moisture inland.
Learn more about weather and weather safety in JetStream - An Online School for Weather.