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Land and sea breezes

By changing the time of day and the heat capacity of the land and sea, we observe temperature differences and changes in the direction of the sea-land wind.

    E08 · Land and sea breezesReady
    You can also experiment with the numbers and controls below the scene.

    Earth Science · Atmosphere · Weather / Principles and Exploration

    Land and sea breezes — principles and investigation

    Even if the sea and land receive the same amount of sunlight, their temperatures change differently because they store different amounts of heat. Change the visual, heat capacity ratio, and solar radiation intensity to look at the surface temperature difference and direction of the sea-land wind. Rather than memorizing the winds of day and night, this activity involves first determining which is warmer.

    How does it work?

    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.

    Key relationship

    C·dT/dt = S(t) − k(T−20 °C)

    Try this investigation

    1. Adjust the time, heat capacity ratio, and solar radiation and run the day. Look at the moment when the indicator and upper arrow change.
    2. Run and record one lap each, starting at noon and dawn. Compare the temperature and wind at the same time 24 hours later.
    3. Maintain solar radiation and time and change the ocean heat capacity ratio from 5 to 2 to compare the difference between the two temperature curves.

    Interpreting your results

    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.

    Assumptions and limitations

    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.