1.8a The Water Cycle
About 70% of the earth’s surface is covered with water. This water evaporates and condenses into clouds. The clouds cause precipitation and this water falls back to the earth’s surface, ready to start the cycle again.
Atmospheric stability tells you how likely it is air will rise and form clouds and precipitation. Unstable air is likely to rise and form tall clouds and often precipitation. Stable air means any air that rises up will sink back to where it came from.
1.8c Lifting Mechanisms
Lifting mechanisms are forms of lift that cause air to rise. In this topic we cover orographic lift, frontal lift, convergence, and convective lift.
1.8d How Clouds Form
Clouds form when moist, warm rising air cools and expands in the atmosphere. The water vapor in the air condenses to form tiny water droplets which are the basis of clouds.
1.8e Precipitation Types
There are many types of precipitation. Rain and drizzle are the only liquid types; the freezing types are snow, sleet, freezing rain, and hail. Hail is unique because it is frozen precipitation that generally only falls from thunderstorms in the summer.
1.8f Cloud Seeding
Cloud seeding is the process where substances like dry ice and silver iodide are put into clouds in an attempt to make precipitation fall. Cloud seeding has also been used to dissipate fog and weaken some storms.