What is weather

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What is weather?

Transcript of What is weather

Page 1: What is weather

What is

weather?

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Weather• Weather it is the condition of the atmosphere

at a particular time and place .

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What can cause the changes of weather?

• Weather variables:

1) Temperature

2) Wind

3)Moisture

4)Precipitation

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How to predict weather ?

1)Weather Balloons 2) Weather satellites

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• 3)Doppler radar

It IIt can detect :1)Precipitation2)Wind direction3) Wind speed

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Insolation • It is the amount of sun energy reaching the

Earth at a given time and place

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What is the angle of insolation?

• a measure of how high the sun is in the sky • measured from the horizon up to the position of the sun

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What happens as the angle increases or decreases?

• As the angle of insolation increases, intensity increases. (heat concentrated in smaller area.)

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• As the angle of intensity decreases, heat is spread out over a larger area.

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Low angle: Less absorbedHigh angle: More absorbed

• Intensity of insolation varies over the Earth because of the curvature of the Earth.

Earth

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Where is intensity the greatest and lowest?

• Intensity greatest near the Equator.

– Sun’s rays are direct

• Intensity low at the poles

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At what time is the angle and intensity of insolation greatest?

•The noon sun has the greatest angle of insolation.

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How to measure angle of insolation ?

• WE can measure ion angle of insolation

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Why does the angle of insolation change between midday and

evening?

The angle of insolation decreases because the Earth’s rotation ,and the air temperature usually decrease

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Measuring Temperature

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Pressure• It is the weight of air pressing on a unit area.

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• The difference of air pressure is due to unequal heating of the Earth.

• Warm air masses have fewer air molecules than cold air masses.

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What is the relation between temperature and pressure ?

As the temperature increases the air particles are far away from each other decreasing the pressure As the temperature increases the pressure decreases

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Air Pressure• Air Pressure is a

measure of the force of the air pressing down on the earth’s surface

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Air Pressure can vary at any particular

point on the Earth depending on the

density of the air

Density = mass / volume

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Convection Cell-Suppose air in an area is cool and under high pressure

-If a near by place is warmer and at a lower pressure

-The air will move from high pressure area to a low pressure area .

This is called “Surface wind”

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• What do you think can increase the intensity of the wind ?

• As the difference in pressure increases the wind intensity increases

• Unequal heating and cooling of air results in difference in pressure

• Where warm air will move

• Up and cold air moves down making a circular pattern of rising and sinking air and wind called “Convection cell”

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Sea Breeze

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Land Breeze

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Instruments used to measure ”Wind and Pressure”

1)Anemometer

A device used to measure wind speed .

The cups spin faster as the wind blow faster

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2)Weather Vane

It is used to measure wind direction . It ‘s a movable arrow that points in the direction the wind blowing .

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3)Barometer

Measures surrounding air pressure against standard air pressure