GEOG 1101 Lecture Notes - Lecture 7: Cumulonimbus Cloud, Hygroscopy, Nimbostratus Cloud
Document Summary
Rain: water vapor condenses into liquid water droplets forming clouds. These droplets coalesce (join together) and become heavy enough to be pulled down by gravity as precipitation (a raindrop), if they do not evaporate before they hit the ground. * cloud droplet average size is about 20 microns in diameter & fall very slowly, about 1000 m/48 hrs. * 1 raindrop = about 1 million cloud droplets, so cloud droplets must coalesce or join together into a raindrop to avoid evaporation. Snow: water vapor condenses into liquid water droplets forming clouds. But also within the clouds water vapor changes to ice crystals by deposition. These ice crystals coalesce (join together) and become heavy enough to be pulled down by gravity as precipitation (a snowflake), if they do not melt before they hit the ground. * two basic mechanisms to explain precipitation formation: * first described by swedish meteorologist, tor bergeron in the early 1930"s.