Meaning and mechanism
Even when receiving the same energy, different heat capacities result in different temperature changes. Land heats and cools more rapidly than water.
During the day, the air over land becomes relatively warmer, leading to upward movement, and air from the sea can flow in near the surface. At night, the opposite phenomenon, known as land breeze, can develop.
Relationships and conditions
In two-box thermal models, the heat capacity multiplied by the rate of temperature change equals the rate of energy entering – the rate of loss. When the heat capacity is larger, the same input of thermal energy results in a slower rate of temperature change.
Actual land and sea breezes are influenced by large-scale winds and coastal topography. A model that simply calculates pressure differences or wind speeds based only on temperature differences is not a realistic one.
What to observe in the simulation
Because the heat capacity of the land is small, temperature changes are rapid and large. The sea breeze during the day and the land breeze at night change depending on temperature differences.
These are two boxes: land C=2 kJ/K, sea C=2×rate kJ/K, and k=0.8 kJ/(h·K). Solar radiation is semi-sinusoidal during the day, minus a certain radiation loss. Use the cycle after the 10-day warm-up. Barometric pressure is a relative value that only indicates the sign of temperature difference and excludes terrain, Coriolis force, and actual wind speed.
Key relationships and symbols
C·dT/dt = S(t) − k(T−20 °C)
| Symbol | Meaning | Unit |
|---|---|---|
| C | Heat capacity of the surface box | J/K |
| ΔT | Temperature difference between land and sea | K |
Worked example
What is the cycle when the land is colder at dawn?
The warm side is relative low pressure, and the cold side is relative high pressure. Surface winds blow from high pressure to low pressure, and in the upper layers they blow in the opposite direction.
Common misconceptions
- Seabreeze is the wind blowing from the sea towards land, and wind blowing from land towards the sea is called land breeze.