Air Masses & Pressure Systems Flashcards
What are the features on a synoptic chart called?
Isobaric Features
What is an Air Mass?
An air mass is a volume of air with many uniform characteristics extending over a large region.
What influences Air Mass characteristics?
The lengrh of time spent over a region the greater the influence of the characteristics of the region.
What is the temperature of Equatorial, Tropical, Polar and Arctic air masses?
Equatorial - Very Warm
Tropical - Warm
Polar - Cold
Arctic - Very Cold
What are the differences in humidity between maritime and continental air masses?
Maritime air mass is relatively humid
Continental air mass is relatively dry
Describe an Arctic Air Mass
Very cold and humid
Wet cold air brings snow in winter
Describe a Polar Maritime Air Mass
Cold and humid
Wet, cold air brings cold showery weather
Describe a Returning Polar Maritime Air Mass
Mild and humid
Moist, mild and unstable air bringing cloud and rain showers
Describe a Tropical Maritime Air Mass
Warm and humid
Warm, moist air brings cloud, rain and mild weather
Describe a Tropical Continental Air Mass
Warm and dry
Hot dry air brings hot weather in summer
Describe a Polar Continental Air Mass
Cold and dry
Hot air brings dry summers. Cold air brings snow in winter.
What are the properties of cold air moving over a warmer surface?
Stability - Unstable with convection
Type of clouds - Convective
Cloud Base - Fairly High, except during precipitation
Precipitation - Showers, sometimes heavy
Visibility - Excellent, except in precipitation
What are the properties of warm air moving over a colder surface?
Stability - Stable and smooth
Type of clouds - Layered
Cloud Base - Generally low
Precipitation - Continuous, light or moderate
Visibility - Poor, with risk of mist, fog or haze
What are the names given to Low Pressure Systems?
Depressions or cyclones
What is the name given to High Pressure Systems?
Anticyclones
