1. Air Masses

2. 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

3. Source Region Geographic Region where the air mass originated Continental = _____________ Maritime = _______________ Tropical = __________________ Polar = ____________________ Arctic = _________________ Over land, dry Over water, wet Lower latitudes, warm Mid to upper latitudes, cool Upper latitudes, cold

4. Air Masses Characteristics mT = maritime tropical = ___________ mP = _____________ = ___________ Warm and moist Maritime polarCool and moist

5. Air Mass Characteristics cT = _________________ = ____________ cP = _________________ = ____________ cA = _________________ = ____________ Continental tropicalDry and warm Continental polarDry and cool Continental ArcticDry and Cold ESRT Page 13

6. mP cP mP mT cT mT

8. Tools Meteorologists Use

9. 1. Station Models How the weather is plotted on a surface map ESRT page 13

10. Station Models 68 66 1212 002.10 Temperature Dew Point Visibility Present Weather Cloud Cover Barometric Pressure Has to be converted Precipitation past 6 hours Wind Direction and Wind Speed

11. ESRT Page 13

12. 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

13. Examples 995.7 = _______ 1023.9 = _______ 957 239

14. 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

15. Examples 678 = ________ 002 = ________ 967.8 1000.2

16. 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

18. Isobars – connect points of equal pressure