Heat makes wind

The idea

Uneven heating of the Earth's surface by the Sun mainly causes the pressure differences that move air from high to low pressure as wind; the same idea explains winds and ocean currents on vastly different scales.

Air on the move

Two patches of ground sit side by side. The Sun heats one more than the other.

What might happen to the air above them?

• Air flows from one patch to the other
• The air stays still
• The air sinks into the ground

Heat, pressure, wind

Press Next step.

From heat to wind

The pressure differences that make wind come mainly from uneven heating of the surface by the Sun. The same idea explains land and sea breezes, global winds and ocean currents, on very different scales.

Uneven heating of the Earth's surface by the Sun mainly causes the pressure differences that move air from high to low pressure as wind. The same idea explains winds and ocean currents on vastly different scales.

Notes

Uneven heating creates pressure differences, and wind is air moving from high to low pressure.

Check yourself

What is wind?

What mainly causes the pressure differences that produce wind?

Which of these is also caused by uneven heating of land and water?

Over a place that is heated more, the warm air …

• The movement of air from a region of high pressure to a region of low pressure — correct. Yes!
• The movement of air from low pressure to high pressure. Wind blows from high pressure to low pressure.
• The rising of warm air. Rising warm air is part of the story. Wind is the movement of air from high to low pressure.
• The ozone layer absorbing UV. The chapter says the pressure differences are mainly caused by uneven heating of the surface by the Sun.
• Uneven heating of the Earth's surface by the Sun — correct. Yes!
• The Earth's gravity holding the air. Gravity holds the atmosphere in place. The pressure differences come mainly from uneven heating.
• The ozone hole. The ozone hole came from human-made CFCs, not from uneven heating.
• Photosynthesis. Photosynthesis is how plants make glucose using sunlight, water and CO₂. It is not a wind.
• Land and sea breezes — correct. Yes!
• Rises, leaving a region of low pressure — correct. Yes!
• Sinks, making a region of high pressure. Warm air rises over a more heated place, creating a low pressure region.
• Stays still. Over the heated place the air becomes warm and rises.