Local Winds by Cara Jones

Local winds are winds that only go short distances.  They occur when air wants to move from high to low pressure areas. Wind speed varies depending on how different the temperatures are. This means if there is a difference of 10 degrees the wind speed is going to be less than and temperature different of 20 degrees.

A sea breeze is a wind that blows from the sea to the land. During the day the sun gives off radiation. When it does the land and ocean both absorbs it’s heat but different amounts. The land heat up and absorbs the heat faster than the ocean because the land doesn't reflect or refract the heat or the light. like the ocean does. When the land is heated up it uses conduction to heat up the air molecules around it. The air molecules are not as heated over the ocean because there is less heat to conduct. This difference in air temperature causes the warm air over the land to become less dense and rise, causing low pressure. While this is happening the cooler, denser air of the ocean is sinking, creating high pressure. Then using convection the winds form.  Then to create the convection we know the air molecules like to go from high to low pressure.

A land breeze is a wind that blows from the land to the sea.  During the night there is no heat source so all of the heat in the surfaces  was absorbed the day before.  The ocean holds on to the little heat it collects better than land. This makes the ocean hotter than the land at night. Because of this, the winds switch creating a breeze that goes from land to the sea.  Like with a sea breeze the heat in the ocean and land heats up the air molecules with conduction. The air on top of the ocean is warmer than the air above the land.  This also means the air on top of the ocean is less dense and has a lower pressure than the air above the land, making the molecules want to go from the land out to the sea.

There are no convection currents at sunrise and sunset because the land a the sea are the same temperature. They heat the molecules above them to the same temperature and there is no less dense place for the molecules to go and therefore no convection current.

Mountain Breeze and Valley breezes are another type of breezes.  A valley breeze is a breeze that happens during the day and goes up the mountain. A valley breeze occurs when the sun heats up the valley and using convection heats up the molecules around the heated land. This causes the warm, low pressure air to rise as the high pressure and cold air push down from the sky.
A mountain breeze is a breeze is a breeze that happens at night.  This breeze happens when the valley is cooling but is still heating the air. This time the air goes straight up the middle because the sides around it are already cool and come down to fill in the space the low pressured air left behind.

This is a Mountain Breeze
http://innovationcharterschool.wikidot.com/mss:king-land-breeze-sea-breeze-mountain-breeze-and-valley-b

 

This is a Valley Breeze http://innovationcharterschool.wikidot.com/mss:king-land-breeze-sea-breeze-mountain-breeze-and-valley-b


This is a video to help your understanding about Local Winds