Key Idea.
Section 1
Cool Air Lifts Warmer Air
Air movement is often a battle of densities. An air parcel that is warmer than its surroundings is less dense (lighter) because its molecules are spread further apart.
The cooler, heavier air around it sinks and pushes the lighter warm air upward. This means warm air doesn't just "rise" on its own; it is buoyed up by the denser cool air underneath it.
Section 2
The Surface Heats the Troposphere
The troposphere is the lowest layer of the atmosphere. Surprisingly, it is heated from the bottom, not the top. Sunlight passes through the air to warm Earth's surface.
The surface then acts like a radiator, warming the air just above it. This is why the atmosphere gets colder the higher you go—you are moving further away from the heat source (the ground).
Section 3
Warm Air Carries Energy Upward
As warm air is pushed upward, it carries thermal energy with it. This vertical transport of heat is called convection.
This process is the engine of weather. By moving energy transfer from the surface to higher altitudes, convection drives the formation of clouds and storms.
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Section 1
Cool Air Lifts Warmer Air
Air movement is often a battle of densities. An air parcel that is warmer than its surroundings is less dense (lighter) because its molecules are spread further apart.
The cooler, heavier air around it sinks and pushes the lighter warm air upward. This means warm air doesn't just "rise" on its own; it is buoyed up by the denser cool air underneath it.
Section 2
The Surface Heats the Troposphere
The troposphere is the lowest layer of the atmosphere. Surprisingly, it is heated from the bottom, not the top. Sunlight passes through the air to warm Earth's surface.
The surface then acts like a radiator, warming the air just above it. This is why the atmosphere gets colder the higher you go—you are moving further away from the heat source (the ground).
Section 3
Warm Air Carries Energy Upward
As warm air is pushed upward, it carries thermal energy with it. This vertical transport of heat is called convection.
This process is the engine of weather. By moving energy transfer from the surface to higher altitudes, convection drives the formation of clouds and storms.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter