What is
weather?
Weather
• Weather it is the condition of the atmosphere
at a particular time and place .
Air Masses
• a body of air extending hundreds or
thousands of miles sideways and sometimes
as high as the stratosphere and...
Types of air masses
Humid Air masses

Dry Air masses
Humidity
It is the amount of water vapor in the air .
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 c...
Air Fronts
• When air masses move across the surface of the
earth they may collide.
• These collisions happen halfway betw...
Types of Air Fronts
Scientists classify fronts by the
characteristics and movements of the two
air masses.
1-Warm Front
When a warm air mass moves into an area
of cooler air ,the boundary between the
air is called
“Warm front”
Th...
• As the warmer air cools ,its relative humidity
increases, and the water vapor condenses
into clouds.
• A warm front usua...
2)Cold Front

• When a cold air mass moves into an area
of warmer air , the boundary between air
masses is called “Cold fr...
• As the warmer air cools ,the water vapor
condenses and form clouds that brings
precipitation
Stationary front
• The boundary between 2 air masses that are not
moving against each other is called
“Stationary front”.
Some of the warmer air mixes with cooler air
,causing clouds to form .
As the clouds are pushed up ,they cool and
produce ...
How fronts are represented
on the weather map?
Global wind pattern
• Wind is the movement of air from an area of
higher pressure to an area of lower pressure.
(Remember:...
Global Winds
• They are winds that blow across long
distances in a predictable patterns.
• Each of these winds carry air masses from one
region to another .
• Each of these winds always blows in the same
directi...
• They curve clockwise in the Northern
Hemisphere and counter clockwise in
Southern Hemisphere .
This curving of the winds is called
“Coriolis effect”
Jet Stream

• Is a band of very strong wind that blows from
east to west high in the atmosphere ,usually
above 6000m .
• J...
• The sudden temperature change causes a huge
difference in air pressure .
• This results in wind speeds of up to 498km/hr
What is weather
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What is weather

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What is weather

  1. 1. What is weather?
  2. 2. Weather • Weather it is the condition of the atmosphere at a particular time and place .
  3. 3. Air Masses • a body of air extending hundreds or thousands of miles sideways and sometimes as high as the stratosphere and having nearly the same conditions of temperature and humidity.
  4. 4. Types of air masses Humid Air masses Dry Air masses
  5. 5. Humidity It is the amount of water vapor in the air .
  6. 6. Pressure • It is the weight of air pressing on a unit area.
  7. 7. • The difference of air pressure is due to unequal heating of the Earth. • Warm air masses have fewer air molecules than cold air masses. Therefore , they are less dense having lower air pressure.
  8. 8. Air Fronts • When air masses move across the surface of the earth they may collide. • These collisions happen halfway between one of the poles and the equator. • The 2 air masses don’t mix much when they collide. • Each keeps its own temperature ,humidity and pressure. • As a result ,a boundary forms, this boundary is called “Front”.
  9. 9. Types of Air Fronts Scientists classify fronts by the characteristics and movements of the two air masses.
  10. 10. 1-Warm Front When a warm air mass moves into an area of cooler air ,the boundary between the air is called “Warm front” The warmer ,less dense air slides up over the cooler denser air in a wide ,gentle slope
  11. 11. • As the warmer air cools ,its relative humidity increases, and the water vapor condenses into clouds. • A warm front usually results in steady rain .
  12. 12. 2)Cold Front • When a cold air mass moves into an area of warmer air , the boundary between air masses is called “Cold front” • The colder ,denser air slides under the warmer air is pushed up .
  13. 13. • As the warmer air cools ,the water vapor condenses and form clouds that brings precipitation
  14. 14. Stationary front • The boundary between 2 air masses that are not moving against each other is called “Stationary front”.
  15. 15. Some of the warmer air mixes with cooler air ,causing clouds to form . As the clouds are pushed up ,they cool and produce light rain or snow . Because the front is not moving ,the precipitation can last for a long time .
  16. 16. How fronts are represented on the weather map?
  17. 17. Global wind pattern • Wind is the movement of air from an area of higher pressure to an area of lower pressure. (Remember: Differences in air pressure is due to uneven heating of the earth.)
  18. 18. Global Winds • They are winds that blow across long distances in a predictable patterns.
  19. 19. • Each of these winds carry air masses from one region to another . • Each of these winds always blows in the same direction • Global winds don’t follow a straight path as they blow from poles toward the equator or from the equator towards the poles.
  20. 20. • They curve clockwise in the Northern Hemisphere and counter clockwise in Southern Hemisphere .
  21. 21. This curving of the winds is called “Coriolis effect”
  22. 22. Jet Stream • Is a band of very strong wind that blows from east to west high in the atmosphere ,usually above 6000m . • Jet streams from along boundaries of large air masses when warm air from the tropics meets air from the poles.
  23. 23. • The sudden temperature change causes a huge difference in air pressure . • This results in wind speeds of up to 498km/hr

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