Last night I talked about some of the terms forecasters use to describe cloud cover. Tonight let's talk precipitation.

Most importantly, there is a difference between "showers" and just plain "rain." Showers are characterized by sudden starts and stops, by sometimes-quick changes in intensity of the rain, and by rapid changes in the sky's appearance - for example, dark clouds one minute, the sun poking out the next. Showers come from bubbly "convective" clouds that develop during the heating of a summer afternoon, for example, or along a powerful cold front.

On the other hand, the term "rain" - without the word "shower" - implies precipitation that lasts longer, perhaps many hours. The precipitation would be steadier in nature, and we might characterize its intensity as "light" or "heavy." Rain, for example, is considered heavy if more than 3/10 of an inch falls in one hour. And in contrast to showery-type weather, the sky on a day when "rain" is forecast would stay gray and cloudy for long stretches of time.