Parallel rows of clouds extend from sea ice across open water in the Bering Sea.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Vertical circulation ×4. prescribed thermal contrast. markers enlarged.

Illustrative local hour 9.6 · right minus left 0.7 °C. Sea breeze: surface flow onshore.

How to read these results

Play follows the chosen daily heating cycle. Real conditions may prevent the night-time reversal shown in the coastal example.

Thermal circulation

Explain how unequal heating creates a circulation, then apply that reasoning to a coastal breeze and an urban heat island.

Drag to rotate. Hold Ctrl and scroll to zoom, or pinch on a touch screen.

Why it happens

Unequal heating can create pressure differences and a circulation. Warm air expands and rises relative to its surroundings, with return flow completing the circulation at another level.

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Cloud streets over the Bering Sea, 20 January 2006. Cold air over warmer water supports convection organised into rolls by the wind.

Try a comparison

Scrub to hour 3 and identify the possible reversal. Select Urban heat and compare city with rural surroundings.

Reading the result

The illustrated circulation isolates differential heating; real winds also depend on rotation, friction and surrounding weather systems.

A common misunderstanding

A sea breeze always blows from sea to land, by day and by night.

A daytime sea breeze can develop when land warms faster than nearby water, creating a circulation with onshore flow near the surface. Overnight cooling may support a land breeze in the opposite direction. Background winds, clouds and coastal terrain can weaken or prevent either circulation.

Cases

Exam language

Sea breeze

A local wind blowing from sea towards land when daytime heating makes the land warmer than nearby water. A circulation develops with rising air over land and return flow aloft. Stronger background winds can weaken or overwhelm it.

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Aqua MODIS, 9 April 2013. Sea-breeze air moves inland and helps cumulus clouds develop over the warmer island. Silvery water is sunglint. This daytime image shows sea-breeze effects, not a night-time land breeze.

Land breeze

A local wind from land towards the sea, commonly at night when land has cooled faster. Larger-scale winds can weaken or prevent it.

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GOES-19, 30 October 2025 at 13:20 UTC. A land breeze keeps clouds away from part of Lake Michigan’s western shore. The product combines visible and infrared observations across the night-to-day transition; station measurements confirm the offshore flow.

Urban heat island

An urban area that is warmer than nearby surroundings, often most evident at night. Surface materials, reduced evaporation, urban geometry and waste heat contribute.

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ECOSTRESS measured London's land-surface temperatures near midnight on 15 July 2022. Built surfaces remained warmer than many vegetated areas. These are surface temperatures, not standard air-temperature readings.

Thermal circulation

A circulation driven by differences in heating and the resulting pressure and density patterns. A sea breeze is a local example, with rising air over warmer land. Rotation and background winds alter larger-scale circulation.

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Cloud streets over the Bering Sea, 20 January 2006. Cold air over warmer water supports convection organised into rolls by the wind.

Onshore flow

Air moving from the sea towards land. It can occur in a local sea breeze or within a larger weather system. The term describes direction relative to the coast, not a fixed compass bearing.

Pressure difference

A difference in pressure between two places. It creates a pressure-gradient force that can start air moving.

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NOAA surface analyses during a late-February 2022 storm. Isobars join equal pressure; front symbols identify analysed boundaries between air masses.

Evaporative cooling

Cooling that occurs when evaporation uses energy from a surface and its surroundings. A moist surface can lose energy as latent heat instead of warming. The effect depends on available water, humidity, wind and incoming energy.

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Evaporation fog over a lake. Water vapour mixes into colder air and condenses into droplets; invisible vapour itself cannot be photographed.

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