Scaffolded notes
Build the idea
Unequal heating drives global circulation
The equator receives more concentrated solar energy than the poles. Warm air tends to rise in low latitudes, move through the upper atmosphere, cool, and sink elsewhere. This creates large circulation cells that transfer energy poleward.
Rotation changes the apparent path
Earth rotates beneath moving air. From Earth's surface, long-distance motion appears deflected to the right in the Northern Hemisphere and left in the Southern Hemisphere. This is the Coriolis effect. It changes direction, not the original source of wind energy.
Three-cell model
A simplified hemisphere contains a Hadley cell from 0 to 30 degrees, a Ferrel cell from 30 to 60 degrees, and a polar cell from 60 to 90 degrees. Real circulation shifts with seasons, continents, oceans, and weather systems.
Stop and explain
Check your thinking
1. What starts global atmospheric circulation?
Possible response: Unequal solar heating and resulting density/pressure differences.
2. Which way is large-scale motion deflected in the Northern Hemisphere?
Possible response: To the right of its direction of travel.
Interactive challenge
Try the science
What is the best description of the Coriolis effect?
Before you leave
Exit ticket
Separate the roles of unequal heating and rotation in global wind.