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: