Scaffolded notes
Build the idea
Fronts are air-mass boundaries
A front forms where air masses with different properties meet. Because cold air is denser, it tends to remain near the surface and force warmer air upward. Rising air can cool and condense into clouds and precipitation.
Cold fronts lift air quickly
At a cold front, advancing cold air undercuts warm air along a relatively steep boundary. Weather can include a narrow band of showers or thunderstorms, gusty shifting winds, a pressure change, and cooler or drier air after passage.
Warm fronts lift air gradually
At a warm front, warm air glides over retreating cool air along a gentle slope. Layered clouds and widespread steady precipitation may develop ahead of the surface front, followed by warmer air after passage.
Stop and explain
Check your thinking
1. Why does warm air rise at a front?
Possible response: Denser cold air stays below and forces the less-dense warm air upward.
2. Which front more often produces a narrow, intense line of weather?
Possible response: A cold front.
Interactive challenge
Try the science
Match the front to the typical clue.
Before you leave
Exit ticket
Compare lifting at a cold front and warm front.