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High and Low Pressure Systems Weather Systems Unit. Regents Earth Science. By the end of this class, you will be able to: *Compare and contrast high and low pressure systems *Identify areas of high and low pressure on a weather map. DO NOW: What’s in a letter?
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High and Low Pressure SystemsWeather Systems Unit Regents Earth Science By the end of this class, you will be able to: *Compare and contrast high and low pressure systems *Identify areas of high and low pressure on a weather map
DO NOW: What’s in a letter? Take a moment to think about what each letter stands for when used on a weather map
Compare/Contrast Chart High and Low Pressure
Identify one center of high pressure and one center of low pressure using the letters on the map below. Be able to briefly explain your answer.
FRONTS • Front: The leading edge of an air mass-branch from low pressure systems
Fronts are shown by lines with symbols that show the type of front and the direction of movement
Fronts- ESRT page 13 • Warm front: an area where a warm air mass is replacing a cooler air mass
What to Expect • Before the front: • cool or cold temps • falling barometer • increasing & thickening clouds • light-to-moderate precip • winds from the e-se, • Temp and dp get closer together/higher humidity
After the front: A. Warmer and more humid weather conditions B. clearing clouds C. a brief rise in pressure D. winds from the s-sw E. Temp and dp are close/high humidity
Cold Front • Cold front: an area where a cold air mass is replacing a warmer air mass
What to Expect • Before the Front: • winds from the s-sw • warm temps • a falling barometer (dropping pressure) • an increase in clouds • a short period of precip • Temp/dp are close; high humidity
Cold Front • After the Front: • winds from the w-nw • a drop in temps • a rise in pressure • showers followed by clearing skies • Temp and DP get farther apart/ lower humidity
Stationary Front • Stationary Fronts: a boundary between air masses that are not moving
What to expect: a noticeable change in wind direction or temperature when crossing from one side of the front to the other
Occluded Fronts • Occluded Front: occur when warm air is pushed above Earth’s surface by cooler air that is closing in from both sides
DO NOT WRITE • A developing cyclone usually has a warm front and a faster moving cold front that wraps around the storm. • An occluded front forms when cold air behind the cold front catches up to the warm front, which is stuck behind the cool air already in place • What to expect: A change in temp., dewpoint or wind direction is possible
Occluded Front Development • Phase 1: • Phase 2
Animation of Fronts <3 Animation of Fronts
Movement of Weather Revisited • Most of the tracks (paths) follow a southwest to northeast pattern because of the United States’ location in the prevailing southwest wind belt • Video: Tying it Together!: Jet Streams, Pressure Systems and Fronts