Air Masses & Fronts
NSF North Mississippi GK-8
ď ľExplain how air temperature, moisture, wind speed and direction, and precipitation make up the weather in a particular place and time. ď ľDescribe how global patterns such as the jet stream and water currents influence local weather in measurable terms such as temperature, wind direction and speed, and precipitation.
NSF North Mississippi GK8
High and Low Pressure Areas
• High pressure causes air to sink • Usually means clear, sunny skies
• Air rises in low pressure areas and forms water droplets • Usually means rain and storms
NSF North Mississippi GK-8
Air Masses
These are two types of air masses: 1. Cold Polar air masses
2. Warm Tropical air masses
NSF North Mississippi GK-8
Fronts A front is the edge between two different air masses
Fronts spread both vertically (up and down) and horizontally (back and forth)
NSF North Mississippi GK-8
NSF North Mississippi GK8
Fronts: Four 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 NSF North Mississippi GK-8
Hint: These sharp points look like icicles. That will help me remember which is the cold front. NSFsymbol North Mississippi GK8
Fronts: Four 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 NSF North Mississippi GK-8
Hint: These bumps look like suns. That will help me remember which symbol is the warm front. NSF North Mississippi GK8
Fronts: Four 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 NSF North Mississippi GK-8
Hint: I have a stationary bike for exercising. I ride and ride, but it doesn’t go anywhere. Neither does this front. Notice that the warm air is pushing one way and the cold air is pushing the other way. NSF North Mississippi GK8
Fronts: Four Types of Fronts 4. Occluded Front: Formed when a cold front catches up to a warm front
This usually results in storms.
NSF North Mississippi GK-8
Summary Four types of fronts: 1. Cold 2. Warm 3. Stationary 4. Occluded
NSF North Mississippi GK-8
Summary ďƒźTwo types of air masses: 1. Continental Polar air masses 2. Maritime Tropical air masses
NSF North Mississippi GK-8
Summary HIGH PRESSURE
LOW PRESSURE
• High pressure causes air to sink
• Air rises in low pressure areas and forms water droplets
• Usually results in several days of clear sunny skies
• Usually results in rain and storms
NSF North Mississippi GK-8
Sources Palmer, Chad and Evans, David. May 20, 2005. Occluded fronts can signal weakening of storm. Accessed 28 October 2005. http://www.usatoday.com/weather/tg/wofront/wofront.htm Palmer, Chad and Kepple, Kevin. May 20, 2005. High-pressure systems brings sunny days. Accessed 27 October 2005. http://www.usatoday.com/weather/tg/whighp/whighp.htm Palmer, Chad and Kepple, Kevin. May 20, 2005. How low pressure systems affect weather. Accessed 27 October 2005. http://www.usatoday.com/weather/tg/wlowpres/wlowpres.htm Weather World 2010, University of Illinois. No date of publication given. Reading and Interpreting Weather Maps. Accessed 21 October 2005. http://ww2010.atmos.uiuc.edu/ (Gh)/guides/maps/home.rxml
NSF North Mississippi GK-8