what is weather

What is

weather?

Weather• Weather it is the condition of the atmosphere

at a particular time and place .

What can cause the changes of weather?

• Weather variables:

1) Temperature

2) Wind

3)Moisture

4)Precipitation

How to predict weather ?

1)Weather Balloons 2) Weather satellites

• 3)Doppler radar

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

Insolation • It is the amount of sun energy reaching the

Earth at a given time and place

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

What happens as the angle increases or decreases?

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

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

Low angle: Less absorbedHigh angle: More absorbed

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

Earth

Where is intensity the greatest and lowest?

• Intensity greatest near the Equator.

– Sun’s rays are direct

• Intensity low at the poles

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

•The noon sun has the greatest angle of insolation.

How to measure angle of insolation ?

• WE can measure ion angle of insolation

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

Measuring Temperature

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

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

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

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

Air Pressure• Air Pressure is a

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

Air Pressure can vary at any particular

point on the Earth depending on the

density of the air

Density = mass / volume

Challenge:

Solution:

Results and

Explanation:

How can you stop the leak in this soda can?

Title: Activity 2. Stop the Leak Date: Feb. 2010

Summary:

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”

• 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”

Sea Breeze

Land Breeze

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

2)Weather Vane

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

3)Barometer

Measures surrounding air pressure against standard air pressure