The Causes of Weather Meteorology
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The Causes of Weather Meteorology

is the study of atmospheric phenomena.. The Causes of Weather. Weather and Climate. Weather. is the current state of the atmosphere, including short-term variations that affect our lives.. The Causes of Weather.

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The Causes of Weather Meteorology

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Presentation on theme: "The Causes of Weather Meteorology"— Presentation transcript:


The Causes of Weather


is the study of atmospheric phenomena.

The Causes of Weather



Weather and Climate

Weather is the current state of the atmosphere, including short-term variations that affect our lives.

The Causes of Weather


describes the average weather over a long period of time and is usually averaged over the course of 30 years or more.

Meteorology, weather, and climate are related.


A Question of BalanceThe Causes of Weather


Air MassesAn

air mass is a large body of air that takes on the characteristics of the area over which it forms.

The Causes of Weather


Air Masses

Classifying Air Masses

The Causes of Weather

Air masses are classified according to their

source regions.

warm and dry continental tropical (



warm and humid maritime tropical (



cold and dry continental polar (



cold and humid maritime polar (



arctic (A)


Air MassesClassifying Air Masses

The Causes of Weather

Each of the major air masses that affects weather in the United States has a similar temperature and

moisture content as

the area over which

it formed.


Air MassesAir Mass Modification

The Causes of Weather


Weather SystemsCoriolis Effect- Deflects moving particles such as air to the right above the equator; caused by Earth’s rotation and combines with the heat imbalance founded on Earth to create the trade winds, polar easterlies, and prevailing


Colder air to warmer areas and warmer air to colder areas.


Wind SystemsTrade Winds (Hadley Cell)

-30 degrees North and South latitude, air sinks, warms, and moves to equator in a westerly direction.

Prevailing Westerlies- flows between 30 and 60 degrees North and South latitude, in a circulation pattern opposite that of the Trade Winds. Surface winds move towards the poles in an easterly direction. Wind blows from the West. Responsible for the movement of our weather in the U.S.

Polar Easterlies-lies between 60 degrees latitude and the poles. Flows from the northeast to the southwest in the Northern Hemisphere. Opposite in Southern Hemisphere. Bring COLD air.




High Pressure SystemGenerally associated with fair, sunny weather

As high pressure is an area of sinking air, and air tends to dry out as it sinks, leaving sunny skies


High Pressure Animation


Low Pressure SystemGenerally cloudy/rainy areas -- where strong areas of low pressure bring our stormiest weather

This is because it's an area of rising air, and as air rises, it condenses into clouds and rain

Air moves from higher pressure to lower pressure, so if you have a high and a low nearby, it can be windy as air rushes between the two


Low Pressure Animation


FrontsWhen two air masses that have different properties meet, they do not mix easily. A boundary forms between the two air masses. This boundary is called a front.

There are four types of fronts:cold fronts, warm fronts, occluded fronts and stationary fronts.

The weather at a front is usually unsettled and stormy.


Cold FrontA cold front forms when a mass of cold air meets and pushes under a mass of warm air

. The cold air mass forces its way underneath the warm air mass and pushes it upward. Violent storms are associated with a cold front. Fair, cool weather usually follows



Warm FrontA warm front forms when a mass of warm air overtakes a cold air mass and moves over it. Rain and showers usually accompany a warm front. Hot, humid weather usually follows



Occluded FrontA cold front travels faster than a warm front. When a cold front overtakes a warm front, an occluded front forms

. As the warm air is pushed upward, the cold air meets cool air. An occluded front may also occur when cool air overtakes a cold front and warm air is pushed upward.

An occluded front produces less extreme weather than a cold or warm front.


Stationary FrontWhen a warm air mass meets a cold air mass and no movement occurs, a stationary front forms.

Rain may fall in an area for many days when a stationary front is in place.