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Name _________________________________________ Date _______________ Period _____________
Investigating the Effects of Colliding Air Masses
Question: What happens when two of the same – and then different – air masses meet?
Hypothesis: ___________________________________________________________________________
_____________________________________________________________________________________
Two cold, moist air masses meeting (two
containers of ice water):
Two warm, moist air masses meeting (two
containers of warm water):
Col
A cold, moist air mass and a hot,
d dry air
W
Col
A cold, moist air mass and a hot,
moist air
d water
W (a container of ice
mass meeting
and
mass meeting (a container of ice water and
a candle):
ate
r
W
ate
r
Col
d
a container of warm water):
ate
r
W
ate
r
Col
d
Data Collection:
Two cold, moist air masses meeting (two
containers of ice water):
Two warm, moist air masses meeting (two
containers of warm water):
Col
A cold, moist air mass and a hot,
d dry air
W
Col
A cold, moist air mass and a hot,
moist air
d water
W (a container of ice
mass meeting
and
mass meeting (a container of ice water and
a candle):
ate
r
Analysis
W
ate
r
Col
d
a container of warm water):
ate
r
W
ate
r
Col
d
A. What did you observe when both tubes contained air with the same temperature and humidity
conditions? Why do you think this happened?
The air was much more stable, there was a little movement, but not much. Because heat transfers
from warmer to cooler areas, if both areas have the same heat and humidity conditions, there will
be no net movement of the heat or the air.
B. What did you observe when the tubes contained air with different temperature and humidity
conditions? Why do you think this happened?
The air moved much more quickly in the convection tubes, there was more mixing of the two
different air masses. Heat transfers from warmer to cooler areas, the movement of heat and the
resulting change in temperature of the air mass causes them to move.
C. Under what conditions do you think winds and rotating storms might form?
When air masses of different temperature and humidity conditions meet, winds and rotating
storms might form.
Reading Questions
1. What is convection?
The movement of heat through air or water (all fluids - liquids and gases).
2. Describe the movement of cold and warm air in a convection current.
Warm air rises in a convection current; cooler air moves in to replace the warm air. As the warm
air rises it expands and cools, this cooler dense air then eventually moves downward toward the
Earth’s surface. Air on the Earth’s surface will once again be heated, expanding and rising.
3. Where do land and sea breezes occur?
Where large bodies of land and water meet.
4. Why do the breezes occur there?
The different rates at which land and water heat and cool, cause these winds to form.
5. Explain how a sea breeze forms.
During the day, land warms up faster than the water in lakes or oceans does. Warm air rises above
the land, forming an area of low pressure. In low pressure areas, the air is warm and light (not
dense). Cool air over the water moves toward land and replaces the rising warm air.
6. Explain how a land breeze forms.
A land breeze occurs in the evenings when the land cools faster than the water does, thus the air
over land becomes cooler than the air over the water. As the warmer air over the water rises, cool
air from land moves in to replace it.
7. What other factors can cause local winds?
Color: darker soils and rocks absorb more heat, thus heating and cooling faster than light grass
and sand nearby. Local uneven heating and cooling of the Earth’s surface can lead to differences in
air temperature above the surface leading to winds.
8. What are global winds?
Winds that are continually forming around the Earth. They move in particular directions and travel
over long distances, they form between the equator and the poles due to large-scale uneven
heating and cooling of the Earth’s surface. The equator receives more direct sunlight making the
areas near the equator very warm, while the poles receive less direct light and the light has to
pass through thicker atmosphere.
9. Why do global winds form? Explain the movement of the air.
Global winds are the result of giant convection currents that circulate within the Northern and
Southern hemispheres of the Earth. As warm air is heated at the equator, it rises and flows both
north and south towards the poles, at the poles the air cools, sinks and flows back towards the
equator again. These air currents are slightly deflected because of the rotation of the Earth on its
axis.
10. What are trade winds and which way do they flow?
Trade winds are a type of global wind. Trades winds flow towards the equator turning west as
they go.
11. Which way to westerlies flow? From west to east.
12. Which way to easterlies flow? From east to west.
13. What happens where westerlies and easterlies meet?
Weather changes occur where the westerlies and the easterlies meet.
14. What is the jet stream?
Long, relatively narrow tubes of strong winds that form in the upper atmosphere.