What it does
Wind is air moving because of differences in pressure. This page shows land on the left and sea on the right, with dots for parcels of air. Warm one side and the air above it expands, gets lighter and rises, leaving low pressure (L). Over the cooler side the air sinks: high pressure (H). Air is pushed from high to low, so wind blows along the ground from the cool side to the warm side, and high up the air drifts back in a loop.
Four scenes show it: a sea breeze by day, a land breeze at night, and the summer and winter monsoons over India.
It follows Class 8 Science, Pressure, Winds, Storms and Cyclones, with more for Class 11 Geography. Before this, standard atmosphere calculator shows how air pressure falls with height; next, cyclone builder shows how the Earth’s spin twists wind into a storm.
How to use it
- Choose a Scene, or set the land and sea temperatures with the sliders. Tap the land or sea to warm it by 2 °C.
- Watch the dots: orange is warm air, blue is cooled air.
- Read which side is warmer, where air rises, where pressure is low and which way the wind blows.
- Switch Level to Class 11 for air density and the pressure 1 km up.
- Pause stops the motion.
Worked example
On the sunny afternoon the land is 34 °C and the sea 27 °C, so the page shows a sea breeze: L over the land, H over the sea. At Class 11 the air over the land has density 101,325 ÷ (287.05 × 307.15) = 1.1492 kg/m³, over the sea 1.1760 kg/m³, so land air is 2.33% lighter. Switch to the clear night: the land is now cooler than the sea and the loop turns round, a land breeze.
Tips
- Land heats and cools faster than water, so breezes change direction between day and night.
- A bigger temperature difference gives a stronger wind.
- The monsoon is a sea breeze lasting a season.
FAQ
Is this a real weather model? No. It is one simple loop to show the idea.
Why low pressure over warm ground? Warm air rises and spreads out high up, so less air presses down below.
Is anything stored? No.
Where the numbers come from
- Wind blows from high to low pressure; warm air expands, becomes less dense and rises; land heats and cools faster than water; sea and land breezes and the monsoon as large-scale versions of them: standard school science found in any textbook.
- Ideal-gas density of dry air ρ = P/(R T) with R = 287.05 J/(kg K) and the isothermal pressure p = p₀ e^(−gz/RT), g = 9.81 m/s²: standard physics.
- The moving air is a single closed convection loop written for this page (a teaching cartoon, not a weather model). The scene temperatures are rounded, made-up values. Checked by tests: the flow has no divergence and no flow through the walls, parcels move toward the warmer side along the ground, the density matches 1.292 kg/m³ at 0 °C, and the pressure with height matches a step-by-step integration.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-10.