Question

In coastal areas, wind current moves from the sea towards the land during the day; but during night it moves from land to the sea. Discuss the reason.

Answer 1

Hint: When air moves from areas of high pressure to areas of low pressure, wind occurs. The reason behind the wind is due to the uneven heating of the earth’s surface by the Sun. Some parts of the earth are cold and some are warm. Warm air rises as it weighs less than cold air. Cool air moves in and it gets replaced by the rising warm air. This movement of air makes the wind to blow.

Complete answer:
Wind is the moving air. Air contracts on cooling and expands on heating. As the warm air is lighter than cool air, it rises up. Whereas relatively cooler air is heavier than warm air, it sinks towards the earth's surface. This occurs due to convection, which is a mode of transfer of heat. As warm air rises up, Air pressure reduces at a place as the warm air rises up; cool air moves in to take the place of the warm air. Winds are produced by variations in air pressure. Wind blows from a region of high pressure to a low pressure region. The wind speed depends on the difference between the air pressures in two regions. When air moves at a higher speed, it creates a low-pressure area.

Due to direct sunlight during the day, land gets more heated up than the sea. Since winds move from a high pressure area to the low-pressure area, wind currents move from sea to the land. Similarly, during nights, land cools down rapidly, but the sea will be warm. It is because water takes time to absorb and release heat. Hence, the direction gets reversed and wind current starts to move from land to the sea.

Note: In summers, sea breezes are stronger than during the winter, because of the large temperature differences between ocean water and land. The fronts caused by the sea breezes along the coast may trigger daily thunderstorm activity in coastal areas.