Essential Questions What is an air mass What

Essential Questions • What is an air mass? • What is the difference between high and low pressure? • What is a front and what are three types of fronts? • How can I read a weather map?

Air Masses • An AIR MASS is a large body of air that has the same temperature and humidity throughout. • Air masses can either be warm or cold.

Air Masses There are two types of air masses: 1. Continental Polar air masses These air masses bring dry and cold air. 2. Maritime Tropical air masses These air masses bring humid and warm air.

High and Low Pressure Areas • High pressure causes air to sink • Usually results in several days of clear sunny skies • Air rises in low pressure areas and forms water droplets • Usually results in rain and storms

Weather Maps: Pressure & Temperature Where are the areas of High and Low Pressure located?

Fronts A FRONT is the border where two air masses meet. Most weather changes occur along a front. ü Fronts extend both vertically and horizontally in the atmosphere

Fronts: Three Types of Fronts 1. Cold Front: The zone where cold air is replacing warmer air • In U. S. , cold fronts usually move from northwest to southeast • Air gets drier after a cold front moves through

Fronts: Five Types of Fronts 2. Warm Front: The zone where warm air is replacing colder air • In U. S. , warm fronts usually move from southwest to northeast • Air gets more humid after a warm front moves through, often causing many hours of precipitation

Fronts: Five Types of Fronts 3. Stationary Front: When either a cold or warm front stops moving • When the front starts moving again it returns to either being a cold or warm front

Weather Maps: Doppler Radar Maps Find the Stationary Front Find a High Pressure system Find a Cold Front

Let’s Review • Low pressure is usually associated with what type of weather? • A. Sunny and fair • B. Cloudy with rain or snow • C. Clear and cold • D. Partly cloudy with a light breeze

Let’s Review • Which of these is a common effect of a warm front? • A. cold, clear weather • B. many hours of rain • C. strong, blowing winds • D. violent thunderstorms

Let’s Review • What kind of air mass causes hot, humid weather? • A. Warm Front • B. Continental Polar • C. Cold Front • D. Maritime Tropical

Let’s Review • A weather map indicated that Chicago, Illinois is in a high pressure system. This means the weather in Chicago is most likely… • A. rainy • B. thunderstorms • C. sunny • D. cloudy

Let’s Review • • • Which of these is liquid precipitation? A. rain B. dew C. fog D. climate

Let’s Review EXTENDED RESPONSE • Suppose it’s sunset on a warm, humid day. After dark, the temperature is predicted to drop. PART A- How does air temperature relate to the amount of water vapor in the air? PART B- What will happen to the water vapor in the air if the temperature drops as predicted?

Let’s Review