Air Masses and Fronts. Air Mass Large body of air with uniform temperature and humidity Air masses...

Air Masses and Fronts

Air Mass

• Large body of air with uniform temperature and humidity

• Air masses take on the characteristics of the region from where they originate

• Continental (dry)• Maritime (moist)• Polar (cold)• Tropical (warm)

NSF North Mississippi GK-8

FrontsA front is the boundary separating air masses of different densities

Fronts extend both vertically and horizontally in the atmosphere

Classified by what type of air mass is replacing another

Where most weather takes place

Types of Fronts

• Cold front• Warm front• Stationary front• Occluded front• Dry Line front

• Each represented by these symbols on a weather map

Fronts: Five Types of Fronts1. Cold Front: The zone where cold air is replacing warmer air

• In U.S., cold fronts usually move from northwest to southeast

• Slope of front is steep so warm air forced up abruptly

• Creates rain and thunderstorms along front

• Air gets drier after a cold front moves through

Fronts: Five Types of Fronts2. Warm Front: The zone where warm air is replacing colder air

• In U.S., warm fronts usually move from southwest to northeast

•Slope of front is gentle so creates a line of stratus clouds and precipitation

• Air gets more humid after a warm front moves through

Fronts: Five Types of Fronts3. Stationary Front: When either a cold or warm front stops moving ( they are in a standoff)

•Bring several days of cloudy, wet weather that can last a week or more.

• When the front starts moving again it returns to either being a cold or warm front

Fronts: Five Types of Fronts4. Occluded Front: Formed when a cold front overtakes a warm front

• This occurrence usually results in storms over an area

• In U.S., the colder air usually lies to the west

Fronts: Five Types of Fronts5. Dry Line (Dew Point Front): Boundary separating a dry air mass from a moist air mass

This occurrence can result in tornadoes being formed

Usually found in western part of U.S.

• New Area of Focus: Fronts

• Warm Fronts and Cold Fronts are caused by air pressure.

• Remember: Cold sinks, warm rises

• Cold Front: Form where cold air moves towards warm air. – Creates rain storms.

Direction of travel

ColdWarm

Cold Warm

ColdWarm

“Honey, I think it’s time to get our stuff together.”

Cold Air

Warm Air

Cold Air

Warm Air

• Video (Optional) Cold Front Time Lapse.– http://www.youtube.com/watch?v=i8zq0UXPLX0

• Warm Front: Form where warm air moves towards cold air.

• Occluded front: When a cold front overtakes a warm front and forces it up (Mix)

• Stationary Front: When a cold front and warm front cannot overtake each other (tie)

• Please match the name of the front to the picture. – Warm Front, Cold Front, Occluded Front,

Stationary Front

• Challenge Activity! Which letter best represents a warm front?

• Challenge Activity! Which letter best represents a cold front?

• Challenge Activity! Which letter best represents an occluded front?

• Challenge Activity! Which letter best represents a stationary front?

• Challenge Activity! Which letter best represents high pressure?

• Challenge Activity! Which letter best represents low pressure?

• Challenge Activity! Which letter best represents a cyclone?

• Challenge Activity! Which letter best represents a cyclone? Answer: A

Weather map fronts. See more at… http://www.nws.noaa.gov/outlook_tab.php

Weather fronts. Learn more at… http://www.windows2universe.org/earth/Atmosphere/front.html

And understanding it holds the key to the past, present, and future

• Video Link Before Quiz– Weather forecasting, fronts, Isobars and more.– http://www.youtube.com/watch?v=lITCF3UPVu4

• Quiz 1-10 Name the Front. Warm, Cold, Occluded, Stationary, Other.

• Bonus -1 pt for each character (1 minute)

• Answers: Name the Front. Warm, Cold, Occluded, Stationary, Other.

Weather Maps

How to read Weather Maps

• There are weather stations all over the world • These stations report on their current weather

using symbols • This data is plotted and a view of conditions

are seen

Station Model

How to read

• Temperature• Weather conditions• Dew point• Atmospheric

pressure• Wind direction and

Wind Barbs• Wind Direction is

stated where it is blowing FROM

• This is blowing from southeast

• Feathers show how fast blowing – Full feather = 10 knots– Half feather = 5 knots– Little feather = 1 knot

Isobars

Temperature Maps

Isobars

• ‘iso’ = equal• “bars” = barometeric pessure

• Shows line of equal atmospheric pressure• Lines close together = strong winds• Lines further apart = gentler winds• Generally measured in 4 millibar increments

• Can also have isotherms on weather maps (measured in 10 degree increments)

Wind Directions• Low pressure system aka “cyclone”– Winds blow in a counterclockwise direction

• High pressure system aka “anticyclone”– Winds blow in a clockwise direction

Air Masses and Fronts. Air Mass Large body of air with uniform temperature and humidity Air masses...

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Transcript of Air Masses and Fronts. Air Mass Large body of air with uniform temperature and humidity Air masses...

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