Download Local Winds (Land Breezes and Sea Breezes)

Local Winds
Why? Winds also exist on a scale that is much smaller than a global scale. Movements of air are
influenced by local conditions, and local temperature variations commonly cause local winds. Local
winds are not part of the global wind belts. Gentle winds that extend over distances of less than 100 km
are called breezes.
1. Sea Breezes
A sea breeze describes a wind that blows from the ocean inland towards land. This breeze occurs most often in the
spring and summer months because of the greater temperature differences between the ocean and nearby land,
particularly in the afternoon when the land is at maximum heating from the sun.
During the day, the sun heats up both the ocean surface and the land. Water is a good absorber of the energy from
the sun. The land absorbs much of the sun’s energy as well. However, water heats up much more slowly than land
and so the air above the land will be warmer compared to the air over the ocean. The warm air over the land will
rise throughout the day, causing low pressure at the surface. Over the water, high surface pressure will form
because of the colder air. To compensate, the air will sink over the ocean. The wind will blow from the higher
pressure over the water to lower pressure over the land causing the sea breeze. The sea breeze strength will vary
depending on the temperature difference between the land and the ocean.
1. What is a sea breeze and when does it occur? 
2. Describe the circulation of a sea breeze.
3. Which rises, high pressure or low pressure?
4. What kind of heat transfer is a sea breeze: radiation, conduction or convection? 
2. Land Breezes
Though land objects absorb heat quickly, they also radiate them very quickly. Which means the air above gets
heated up and becomes light. The warm air starts to rise and low pressure is created above the surface of land.
The air above the surface of water being cold is denser and heavier, causing high pressure over the surface. This
pressure difference causes winds to blow from sea to land during the day.  (over) 
What happens after sun set? The thermal coefficient of water is high meaning water cannot radiate heat quickly.
Though water absorbs less heat during the day, it retains the heat. Now the sea is warmer than the land. So, the
winds blow from high pressure area (land) to low pressure area (sea).
Winds blowing from the land to the sea is called land breeze and that blowing from the sea to the land is called sea
breeze.
1. Describe the circulation of a land breeze.
2. When does a land breeze occur? 
3. Which heats up and cools more quickly, land or ocean? 
4. Which is denser, cold air or warm air?
3. Mountain and Valley Breezes
During the daylight hours in mountainous regions, a gentle valley breeze blows upslope. This valley breeze forms
when warm air from the valleys moves upslope. At night, the mountains cool more quickly than the valleys do. At
that time, cool air descends from the mountain peaks to create a mountain breeze. Areas near mountains may
experience a warm afternoon that turns to a cold evening soon after sunset. This evening cooling happens because
cold air flows down mountain slopes and settles in valleys.
1.
What is a valley breeze and how does it form? 
2.
What is a mountain breeze and how does it form? 
3.
When does a valley breeze form?
4.
When does a mountain breeze form?