Convection is defined as what?

• A. Warm air rises and cool air sinks; this creates convection currents in the atmosphere
• B. The horizontal movement of air due to pressure differences
• C. The process by which water vapor condenses into droplets
• D. The stable stratification of the atmosphere with no vertical motion

Answer: (A)

Convection is the vertical transport of heat and energy by buoyancy in the atmosphere. When air near the surface is warmed, it becomes less dense and rises; cooler, denser air sinks to take its place, setting up a vertical circulation that moves heat upward. This rising motion can also lift moisture, leading to cloud formation as the rising air cools and moisture condenses. The other ideas describe different processes: horizontal movement due to pressure differences is advection, not convection; condensation is a phase change that can occur without vertical transport; and a stable layer with no vertical motion means convection isn’t happening.