Title: Air Masses and Weather Fronts Brown 24-25
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# Air Masses & Weather Fronts Weather Map Observations
List 5 things you either see ,
know , or wonder about: 1. there is an H over Georgia, this means heatwave so Georgia is hot today. OR 2. There is an H over Georgia, I wonder what that means? What is an Air Mass? How does it influence weather
An air mass is a large body of air defined by its temperature and humidity characteristics and bordered by fronts As the air mass moves, i t brings its temperature & humidity with it causing daily fluctuations in temp. & humidity Its temperature and humidity characteristics are determined by where it was formed Polar (P) from mid-high latitudes (33-65 ) = cold
Tropical (T) from low latitudes (0-32 ) = warm
Characteristics & Classification of Air Masses
Maritime (m) originates over ocean = humid
Continental (c) originates over land =
dry
Polar vs. Tropical vs. Arctic Maritime vs. Continental
Arctic (A) from high latitudes (66-90 ) = very cold What is the Jet stream?
-The Jet stream is a fast flowing river of air at the top of the troposphere with wind speeds often greater than 100 mph -It forms at the boundary zone between Polar and Tropical Air masses. -It flows from west to east. Weather Fronts
Weather Front : boundary between 2 air masses of different temperatures (T) or humidity (hum) that meet up Named by air mass that is
MOVING INTO REGION -war
Like a front in a war: it is where two different forces meet How to identify a front on a weather map or by personal observation:
Look for: Sharp temperature changes over a relatively short distance Change in humidity Rapid shifts in wind direction Pressure changes Clouds and precipitation patterns (more clouds & precip on front) We are going to correctly DRAW the symbols for the 4 weather fronts! Get some colored pencils/markers/pencils/pens Colors you need: Blue, Red, and Purple 4 Types of fronts
Warm : Cold and warm air masses moving in the same direction, but a warm air mass moves faster and overtakes the cold air mass.
Cold : Convergence of a cold and warm air mass.
Occluded : Air mass sandwich when a warm air mass gets caught in between two cold air masses.
Stationary: A cold and warm air mass move parallel past each other in opposite directions. Map View vs Cross-Sectional View Warm front cross-section
Generally associated with cirrus clouds followed by stratus/nimbostratus type clouds, for an extended period there are overcast skies and/or light to moderate precipitation Cold front cross-section
Cumulonimbus clouds along the front in the warm air, producing thunderstorms / heavy precipitation as well as severe weather at times (hail and tornadoes) over a short period of time Map view of cold and warm fronts Occluded front cross-section and map view
Complex weather Clouds found here are a complicated mixture of those associated with both warm and cold fronts Heavy rain in the warmer months and blizzards in the colder months Stationary front cross-section
The two air masses reach a stalemate Temperature and wind conditions can remain stagnant for days Extended period of relatively widespread cloudiness and/or light precipitation Clouds found here are all types of stratus clouds ( stratus ,alto stratus , cirro stratus ,nimbo stratus )Why does the warm air always lift?
The temperature and humidity differences make the masses different densities. Air is bad at transferring its heat.mixing happens slowly especially if there is no turbulence Warm humid air is less dense so it always goes up
DEMO TIME! What is this?
A) Orographic lifting B) Frontal wedging C) Convergence D) Local convective lifting