Lesson 5.1Weather

*Refer to Chapters 10 & 11 in your Textbook

Learning Goals:

1. I can analyze how wind circulation and coriolis develop air masses.

2. I can differentiate between the 4 types of weather fronts.

3. I can use weather fronts and pressure systems to make weather predictions.

Wind Circulation: Warm, moist air risesCold, dry air sinks This creates a circulation of air called an air cell: 1. Hadley Cell: equator

2. Ferrel Cell: mid-latitude 3. Polar Cell: poles

Wind Circulation: *Label Map!*Coriolis and the air cells heating and cooling allow

the winds to travel in specific directionsTradewinds: occurs along the equator, carries cool

air from the northeast to the southwest Westerlies: occurs at the mid-latitudes (above the

Tropic of Cancer in the North), carries warm air from the southwest to the northeast

Polar Easterlies: occurs at the north and south poles, carries extremely cold air from the northeast to the

Wind Circulation:

Air Masses: An air mass is a volume of air defined by its

temperature, location, and water vapor contentm (maritime): moist, over the oceanc (continental): dry, over the landT (Tropical): warm airP (Polar): cold airA (Arctic): coldest air

Weather Fronts: Weather fronts are boundaries between two air

masses of different temperature 4 Types:1. Warm Front2. Cold Front3. Occluded Front4. Stationary Front

Weather Fronts: Warm fronts occur when warm air replaces cold air The warmer air rises creating small clouds and light

rain that can last a long time, and an increase in humidity

Warm fronts move much slower than cold fronts

Weather Fronts: Cold fronts occur when cold air replaces warm airCold fronts move much faster than warm, which

causes the warm air to rise vertically quickly This creates heavy clouds and thunderstorms that

are quick, before the air cools down and humidity decreases

Weather Fronts: Occluded fronts occurs when a cold front over

takes a warm frontThis happens when very cold, cool, and warm air collide with each otherActs like a cold front creating heavy clouds and rain or snow

Weather Fronts: Stationary fronts occurs when a cold front meets a

warm front, but there is not forward movement (“standing still”)

Acts like a warm front creating clouds and light rain or snow that can last a long time

Pressure Systems: What else can we use to predict weather patterns besides weather fronts? = Air Pressure Average Air Pressure = 980 – 1050 mb (millibars) High Pressure System: good weather, low humidity, low clouds, no precipitation Low Pressure System: bad weather, high humidity, many clouds, rain, snow, or cyclones

Pressure Systems: