The Study of the Entire Atmosphere,

Including Its Weather.

WEATHER- The state of the atmosphere at a given time and place

To predict the weather you need to observe the clouds, wind, temp., humidity, air pressure and precipitation over a period of time.

Energy from the sun results in changes in the weather. Heat moves through the atmosphere in three ways:

•Radiation

•Conduction

•Convection

SOLAR ENERGY THAT REACHES THE EARTH; WE RECIEVE ONE TWO-BILLIONTH OF THE SUN’S RAYS

Greenhouse gasses, carbon dioxide (CO2), water vapor and methane (CH4) act like the glass. Less heat escapes. This causes Global Warming.

•As the Sun warms the land, clouds form when moisture laden warm air rises and expands.

•Above the surface this air reaches an altitude where the temperature is below the dew point.

•It then cools and condenses and cloud droplets form on condensation nuclei.

• The falling of any form of water from the air to Earth’s surface.

• Occurs when cloud droplets grow into drops heavy enough to fall to Earth.

• Type of precipitation depends on temperature.

• Much of the weather in the U.S. is a result of the invasion of air masses.

• An air mass is a large body of air with similar characteristics of air pressure, temperature and moisture.

• Air masses that form over land (continental) are dry.– If they form in Canada they are also cold. (cP)– If they form in the Southwest or Mexico they are warm.

(cT)

• Air masses that form over water are moist.– If they form off the coast of Canada they are also cold.

(mP)– If they form in the Gulf of Mexico they are also warm.

(mT)

• Continental Arctic (cA) – really cold and dry

• Continental Polar (cP) – cold & dry

• Continental Tropical (cT) – warm & dry

• Maritime Polar (mP) – cold & moist

• Maritime Tropical (mT) – warm and moist

1. Cold air is advancing and replacing warm air

2. Cold fronts are steeper and move faster than warm fronts

3. The air rises upward rapidly forming cumulonimbus clouds

4. Heavy precipitation and thunderstorms which start and end quickly are associated with cold fronts

5. When the front passes the air is cooler and dryer.

Map Symbol

very steep front

Thunderstorm Stages

1) Warm air is advancing and replacing cold air.

2) Warm fronts move slower; Warm fronts have a gentle slope.

3) Warm air may travel 1,000 km before rising 2 or 3 km.

4) Warmer temperature follow the passing of a warm front.

Mid-latitude Cyclone

Highs and Lows

• High pressure systems are associated with fair weather.

Winds blow clockwise and out.• Low pressure systems are associated with stormy weather. Winds blow counterclockwise and in.

1. A cold front is advancing and combining with a warm front.

2. Warm air is lifted above the surface between cold and cool air.

• Occluded fronts move the slowest of all (20 mph).

Precipitation occurs for about 400 miles, most of which is in front of the frontal boundary

Cool air is in front, as warm air is forced up by cold air which follows the passing occluded front

A stationary front is a boundary between two different air masses, neither of which is strong enough to replace the other. When a warm or cold front stops moving, it becomes a stationary front.

• Orographic precipitation - precipitation generated by a forced upward movement of air upon encountering mountains. • Upon ascent, the moisture laden air that is being lifted will expand and cool and clouds form.• More cooling causes precipitation.• A wetter climate prevails on the windward side of a mountain.• Drier air is left on the descending, generally warming, leeward side •where a rain shadow is formed.

Why does it rain on one side of a mountain range?

Windward Leeward

Cortlandt Manor – Average Annual Precipitation is 52 in.