LOCAL WINDS

LOCAL WINDS These winds affect only a limited area and blow for short periods of time, and are generated by immediate influences of the surrounding area. Most local winds are developed by depression: these are of consid­erable environmental importance as they may affect the plants and animals when dry and extremely hot or cold.

Land and Sea Breeze When a region is hotter than the neighbouring region, air from the cooler region moves into the hot region to take the place of the hot air which has expanded and risen. During the day the land gets warmer than the sea producing low pressure over the land into which cooler air moves from over the sea. Thus the local wind that blows from sea to land during the day is called sea breeze. It reaches the maximum strength during the mid­afternoon when temperature difference between the land and the sea is greater, and dies out by the evening as the sun's heat diminishes. It is best developed in tropics when conditions are calm and the sky is clear, but can also be observed in temperate areas under similar conditions. It is greatly variable. During the night the land cools more quickly than the sea and a reverse process sets in LAnd breeze is a cool wind that blows from the land to the sea (or a large lake, etc.) during the night.

It occurs when night time radiation cools the land and the air in contact with the ground surface. The atmospheric pressure over the land is raised relative to that over the sea resulting in a difference of pressure and the flow of air towards the sea from land. Land breeze is most common in tropical areas but may also occur in high latitudes particularly when the weather is calm. Land breeze is not as strong as sea breeze.