Weather—Understanding it

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Weather—Understanding it

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Weather

Why is it so important to understand the weather?

Weather

Is the atmospheric conditions, along with short-term changes, of a certain place or certain time

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Tools to Measure Weather Thermometer- temperature Barometer- air pressure Anemometer- wind speed Rain gauge- rain fall Psychrometer- humdity

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Tools to measure Weather

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HEATING THE EARTH

Factors of the atmosphere that interact to cause weather Heat energy Air pressure Winds Moisture

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Heat Energy and the Atmosphere Most of the sun’s heat is absorbed

through the atmosphere. The sun’s radiant energy helps to

warm the atmosphere. It is reflected back into space

which can be Absorbed by clouds, earth’s

surface, scattered in the atmosphere, absorbed by ozone

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Air Pressure

Air pressure is the pressure that a column of air exerts on the surface below it.

Depends of the density of the air

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Factors affecting air pressure Three main factors

Temperature Water Vapor Elevation / altitude

High Pressure A large body of circulating

air with high pressure at its center and lower pressure outside of the system. (air moves into and down). Air moves from high

pressure to low pressure. This air is called wind.

The dense air sinks and brings clear skies and fair weather.

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Low Pressure A large body of circulating air

with low pressure at its center and higher pressure outside of the system.

Air on the outside of the system will spiral in toward the center.

This causes the air inside the system to rise causing the air to cool and condense.

Weather in this system is cloudy and rainy. 04/21/23 12

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Moisture in the Air

Humidity- the amount of water in the air

Relative humidity is the amount of water vapor present in the air compared to the maximum (100%) amount of water vapor the air could contain at that temperature

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Weather Patterns

Air masses– cover thousands of sq kilometers

Air masses are formed from changes in weather causing large bodies of air to move.

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Four types of air masses

Maritime Tropical– forms over ocean near equator Holds warm moist air When in contact with cold air in

winter- snow or rain fall Maritime Polar– forms over the Pacific

Ocean in both winter and summer Brings cooler weather to the eastern

states and fog to the western states.

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Air masses

Continental Tropical– forms over land in Mexico. Brings hot, dry air to the SW states.

Continental Polar- forms over land in Northern Canada In winter, brings cold, dry air to the

US.

http://video.about.com/weather/Types-of-Air-Masses.htm

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FRONTS

When 2 air masses such as warm and cold meet they form a boundary instead of mixing. FOUR TYPES OF FRONTS

Cold Warm Occluded Stationary

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fronts

Cold– meet and push under a warm mass of air Travels faster than a warm front

Warm– overtakes a cold front and moves over it

Occluded– when cool air overtakes a cold front and warn air is pushed upward.

Stationary– two fronts meets but do not move.

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Lines on a Map

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