Clouds appear out of clear sky and then, sometimes, it rains. This short course follows water from invisible vapor to a falling drop: how much water air can hold and what the dew point means, how rising air builds a cloud (and why droplets need a speck of dust to form on), what finally makes droplets heavy enough to fall, and why the same storm can drop rain, snow, sleet, or hail.
Clouds appear out of clear sky and then, sometimes, it rains. This short course follows water from invisible vapor to a falling drop: how much water air can hold and what the dew point means, how rising air builds a cloud (and why droplets need a speck of dust to form on), what finally makes droplets heavy enough to fall, and why the same storm can drop rain, snow, sleet, or hail.
