Convection

Imagine a pot of water on a stove. As the heat turns up, tiny bubbles start rising from the bottom.

Why does all the water in the pot get hot when only the bottom is being heated?

This happens because of convection, the movement of heat through liquids and gases as warm particles rise and cooler particles sink.

When you boil water, the heat from the stove warms the water molecules at the bottom.

These hot water molecules rise, and cooler water molecules move down to take their place.

This continuous cycle of rising and sinking water molecules heats the water evenly.

Let’s look at some familiar examples of convection.

During the day, the land heats up faster than the sea and warms the air above it. This warm air rises over the land, and cool air from the ocean moves in to replace it.

This is why we feel a cool breeze from the sea.

During winter, at home, a heater warms the air near the floor. The warm air rises while cooler air moves down, spreading heat throughout the room.