Download Air Masses

Air Masses
From: http://earthstorm.ocs.ou.edu/
Editor: Stephanie Nardei
Time:
1 Period
Preparation
Time:
5 minutes-making copies
Materials:
From http://earthstorm.ocs.ou.edu/materials/les_airmasses.php
Mesonet temperature map
Mesonet dewpoint temperature map
Air Mass Student Sheet I
Air Mass Student Sheet II
Colored pencils
Abstract
Where toxicants of environmental health importance are transported through the air,
understanding the natural processes which contribute to air movement and weather patterns of a
region is important. For example, in some cities inversion layers trap pollutants close to the
ground. Students will examine physical characteristics of several types of air masses. Students
will discover air masses can be identified and defined by their temperature and moisture content.
Purpose – Explanation of how air masses affect local weather, causing transfer of environmental
health toxicants.
Objectives
Students will be able to:
1. Categorize air bodies by temperature and moisture characteristics on given maps.
2. Recognize large regions of similar type air on given maps.
3. Describe similarities and differences between air temperatures on the given map,
Describe similarities and differences between dew point temperatures on the given map
National Science Education Standard:
CONTENT STANDARD D: Earth and Space Science
ENERGY IN THE EARTH SYSTEM



Earth systems have internal and external sources of energy, both of which create heat. The
sun is the major external source of energy. Two primary sources of internal energy are the
decay of radioactive isotopes and the gravitational energy from the earth’s original formation.
Heating of earth’s surface and atmosphere by the sun drives convection within the
atmosphere and oceans, producing winds and ocean currents.
Global climate is determined by energy transfer from the sun at and near the earth’s surface.
This energy transfer is influenced by dynamic processes, such as cloud cover and the earth’s
rotation, and static conditions, such as the position of mountain ranges and oceans.
GEOCHEMICAL CYCLES

Movement of matter between reservoirs is driven by the earth’s internal and external sources
of energy. These movements are often accompanied by a change in the physical and
chemical properties of the matter. Carbon, for example, occurs in:
a. carbonate rocks such as limestone,
b. atmosphere as carbon dioxide gas,
c. water as dissolved carbon dioxide, and
d. all organisms as complex molecules which control the chemistry of life.
Teacher Background
When a large body of air remains over an area for several days or weeks, the body of air may
change its’ thermal and moisture properties according to the land or water under it. The air
exchanges heat with the land or water, either warming or cooling, until it’s’ temperature closely
matches the surface below. The body of air also gains or loses moisture depending on the
temperature and surface moisture content. A body of air resembling characteristics of the surface
under it is called an air mass.
Related and Resource Websites
http://k12.ocs.ou.edu/teachers/lessons/airmasses.html
Air Masses Scaffolding Activity: http://ww2010.atmos.uiuc.edu/(Gh)/guides/crclm/act/arms.rxml
Article on USA Today on Air Masses:
http://www.usatoday.com/weather/tg/wamsorce/wamsorce.htm
Online Guide on Air Masses & Fronts:
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/af/home.rxml
Oklahoma Meteorology on Air Masses: http://okfirst.ocs.ou.edu/train/meteorology/AirMasses.html
Geography 101: The Physical Environment on Air Masses & Fronts: h
http://www.uwsp.edu/geo/faculty/ritter/geog101/uwsp_lectures/lecture_fronts.html
Activity
1. Select maps for your state. Maps should show two different air masses within the state. A
good example is when a cold front is moving across the state, preferably with continental
polar and maritime tropical air masses. (If unavailable, Oklahoma maps are available at the
addresses listed in the materials section)
2. Divide the class into groups of 3 or 4 students.
3. Distribute Protocol Sheets and allow students time to complete as you walk around assisting.
4. When the students circle the warm, cool, moist, and dry regions, be sure they do not use
small circles around only a few stations. Try to get them to see a large region (e.g., ½ or ¼
of the state) as warm or cool, moist or dry.
5. Students may need to be reminded that dew point temperature is an indication of the
moisture amount in the air.
Provide students with the following
PROCEDURE
1. Obtain one temperature map and one dew-point temperature map for each student in your
group.
2. Contour the temperature map and dew point map every 10 degrees.
3. Circle the region on your map containing the warmest temperature readings. Use a red pencil.
4. Circle the region on your map containing the coolest temperature readings. Use a blue pencil.
5. Circle the region on your map, containing the highest dewpoint temperatures. Use a green
pencil.
6. Circle the region on your map containing the lowest dew point temperatures. Use a brown
pencil.
QUESTIONS
1. Where are the warmest temperatures? Are the dew points high or low in this region? Label this
region A.
2. Where are the coolest temperatures? Are the dew points high or low in this region? Label this
region B.
3. If you were to describe the regions as "warm and dry", "warm and moist", "cool and dry", or
"cool and moist", how would you describe region A? Region B?
4. The Northern Hemisphere can be divided into three "latitudinal" regions:
a. the polar region, between 0°N and 30°N,
b. the middle latitudes, between 30°N and 60°N, and
c the tropics, between 60°N and 90°N.
Where do you think the air in region A came from? Why? Region B? Why?
5. What do you think causes air to be moist or dry? Why?
6. How specific can you get predicting where a region of air is originally from?
7. How can you predict these regions? What does this say about how "air masses" are formed?
8. Based on our class data and discussions, what can you say about the source and
characteristics of the air which covers large state regions?
9. Discuss observations using the discussion sheet provided. You may want each group of
students to write their answers before discussing them with the class. Ask students to research
the air masses which apply to their home town. How might these impact environmental health
issues?
Embedded Assessment
Can students categorize air masses by temperature and moisture? Can students recognize
similarities and differences between temperatures and dew points?