So I’ve noticed that any time I’ve gone to the beach relatively early in the morning the sea is really calm. Practically no waves and really still. Is there any reason for this?
In: Earth Science
Yeah during night it’s colder and the sea and the land will have a similar temperature.
When there is only a small temperature difference there will be less wind, and without wind there are no waves.
In the absence of any large weather system wind you basically have two winds on the coast: Sea breeze and land breeze.
Sea breeze is wind coming in from the sea and is caused by the sun heating the ground and happens during hot days. Land breeze is wind going out to sea and is caused by the cooling of the ground and happens during the night. So you have wind blowing out to sea at night.
Also, wind causes waves by gently/violently pushing the top most layer of the water.
So at night and in the morning you basically have winds that cause waves going out to sea but not coming in from the sea. During the day it reverses and you have wind and waves coming in from the sea.
There are two types of waves which can turn a flat sea into a rougher one – swell waves and wind waves.
Swell waves can arrive at any time of day, but because wind waves are generated by the wind, they only develop when the wind begins to blow steadily. Since wind speeds are often low at night, and increase during the daytime, wind waves often die out during the night, leading to a relatively flat sea (perhaps with swell waves) in the early morning. During the day, the wind waves increase in size as the wind speed increases, leading to a rougher, more choppy, sea surface during the afternoon and evening.
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