An air mass is a large body of air with relatively uniform temperature and humidity characteristics. Air masses form over large land or water surfaces and take on the temperature and moisture characteristics of these surfaces where they remain stationary for days, or even weeks. Their temperature characteristics are classified as maritime or continental. The following types of air masses result:
/ Maritime equatorial (mE)/ Maritime tropical (mT)
/ Maritime polar (mP)
/ Continental tropical (cT)
/ Continental polar (cP)
/ Continental arctic (cA)
Note: Continental equatorial and Maritime arctic air masses are rarely found. Air masses often migrate from their source regions and affect mid-latitude weather. Examine the diagram below showing air masses affecting North America.
1. Based on the source regions shown by the ovals, use the appropriate two-letter code to indicate each air mass type.
2.Air masses over land are ______than over water. Air masses over tropics are ______than higher latitudes.
Air at the surface moves from ______pressure to ______pressure at a front
As it moves into the low, it forces the warm (less dense) air ______
The rising air ______at high altitudes and reaches its dew point. This allows
______to form.
3.
WARM:
Caused by:
Weather associated with it:
Other info:
Cold:
Caused by:
Weather associated with it:
Other info:
Occluded:
Caused by:
Weather associated with it:
Other info:
Stationary:
Caused by:
Weather associated with it:
Other info:
4.The boundary between air masses can be characterized by changes in three characteristics including:
5.Explain why freezing rain more commonly occurs with warm fronts than with cold fronts.
6.You are in Ithaca, NY and observe the wind shifting from East to South accompanied by a sudden rise in both the air temperature and dew point temperature. What type of front passed?
7.
Middle-Latitude Cyclone
Located:
Caused by:
Six stages of the life cycle of a middle-latitude cyclone:
1.
2.
3.
4.
5.
6.
8.List 2 locations where you might commonly see a front developing in the initial stage of a middle-latitude cyclone (Hint: think about clashing air masses):
9.Draw and label the 1004, 1008,1012 and 1016 isobars. Label the low pressure. Then, draw the frontal boundary(ies) in the figure below:
10.Use the following weather map to help fill in the table below:
Point / Temperature (Warm or Cold) / Pressure (Rising or Falling?) / Precipitation / Type of Clouds / Wind Direction1
2
3
4
5
11.The following 4 weather maps depict 6 hour intervals in what was known as the “Storm of the Century” or the Blizzard of 1993. These maps show isoheights (lines of equal height…they are dotted) and isobars. You will only really need to pay attention to the isobars. Your group will be responsible for handing in just one copy of all them. Please make sure to include all your names on each! Each member of your team should be responsible for drawing in the low pressure and associated fronts on one map and the whole team should approve of the locations prior to finishing! Make sure the location of the lows and fronts makes sense with regards to the time stamps! Draw your fronts with the correct symbols and the correct colors! (note the time stamps on the top right of each map) When trying to determine the location of fronts, look for the “kinks” in the isobars. They usually point like an arrow AWAY from the Low pressure. Finally, use several large arrows to show the overall wind pattern around the fronts and Low on the map.
After finishing with your maps, please answer these final questions:
12.What was the minimum pressure of this mid-latitude cyclone at each 6 hour interval? Is the cyclone getting stronger or weaker?
13.Do you notice any stages in the cyclones development? Is there any occlusion by the final map?
14.What air masses do you think clashed in the formation of this low pressure system and associated fronts?
15.According to the weather maps, where are the winds blowing the strongest? How do you know?
16.Thunderstorms have formed along a cold front producing rain showers on the cold-air side of the front. Assuming that the air on the cold-air side of the front is initially sub saturated, will the rain showers increase the temperature difference across the front (frontogenesis) or decrease the temperature difference across the front (frontolysis)? Explain