Air Masses
Definition
Large body of air having similar temperature and moisture
Air masses extend several miles up and cover lots of “ground”
There can be several different air masses over the US at any given time
Source Region
• Geographic Region where the air mass originated
• Continental = _____________• Maritime = _______________• Tropical = __________________• Polar = ____________________• Arctic = _________________
Over land, dryOver water, wet
Lower latitudes, warmMid to upper latitudes, cool
Upper latitudes, cold
Air Masses Characteristics• mT = maritime tropical = ___________
• mP = _____________ = ___________
Warm and moist
Maritime polar Cool and moist
Air Mass Characteristics
cT = _________________ = ____________
cP = _________________ = ____________
cA = _________________ = ____________
Continental tropical Dry and warm
Continental polar Dry and cool
Continental Arctic Dry and Cold
ESRT Page 13
mP cP
mP
mT
cTmT
Tools Meteorologists Use
1. Station Models
• How the weather is plotted on a surface map
• ESRT page 13
Station Models
68
66
12
002
.10
Temperature
Dew Point
Visibility
Present Weather
Cloud Cover
Barometric PressureHas to be converted
Precipitation past 6 hours
Wind Direction and Wind Speed
ESRT Page 13
Converting the air pressure for the station model
• If the air pressure is 986.8 mb drop the 9 and the decimal and put 868 on your station model
• If the air pressure is 1009.8 drop the 10 and the decimal and put 098 on your station model
• Examples
• 995.7 = _______
• 1023.9 = _______
957
239
Reading the air pressure from the station model
• Look at your station model number, if its greater than 500, add a 9 and put a decimal between the last 2 numbers
• Look at your station model number, if its less than 500, add a 10 and put a decimal between the last 2 numbers
Examples
• 678 = ________
• 002 = ________
967.8
1000.2
2. Surface maps• Station models are plotted and then analyzed-• Usually for isotherms and isobars, high and low
pressure, fronts, precipitation, etc.• Isotherms: Lines of equal
_________________________• Isobars: Lines of equal
______________________• = isobars close on a weather map mean the
wind speed is __________(higher pressure gradient)
temperature
isobars
higher
Isobars – connect points of equal pressure