Assignment KEY

Temperature Inversions – KEY
Use these resources to guide your research:
1. Differentiate between temperature inversions and a normal weather situation.
Normal: air temp decreases as altitude increases, air is unstable and flows between warm and cool
areas > spreads around pollutants
Inversion: temperatures increase with increasing altitude. Warm, less dense air mass moves over a
dense, cold air mass. The warm inversion layer then acts as a cap and stops atmospheric mixing.
Stable air mass.
2. How do temperature inversions form?
cold air can enter from an outside area and flow along the ground below the warmer air (the density is
different so they form two distinct layers)
ground cools at night which cools the air that is in contact with the ground – air is a poor conductor of
heat so the air higher up remains warm
can also happen when cold air flows from mountain peaks down into valleys. This cold air then pushes
under the warmer air rising from the valley, creating the inversion.
cold ocean or lake water can decrease surface air temperature and the cold air mass stays under
warmer ones.
3. Where and when are they most likely to occur?
 some coastal areas (from cold water cooling the air above it)
 form in valleys (as cold air is trapped by warm air on top)
 areas with significant snow cover because the snow at ground level is cold and its white color reflects
almost all heat coming in. Thus, the air above the snow is often warmer because it holds the reflected
calm conditions (prevent mixing of air)
clear skies (increase rate of cooling at Earth’s surface)
long nights (more cooling of ground and air temp)
more likely in winter
4. What are the effects / consequences?
normally pollutants are circulated away, but an inversion traps them in the cold layer which results in
freezing rain (snow melts when it hits the warm air, then supercools as it passes through the cold air)
thunderstorms and tornadoes because of the intense energy that is released after an inversion blocks
an area’s normal convection patterns.
Severe inversions cause respiratory problems
5. How do they go away?
weaken during the day and disappear as the sun warms the Earth's surface.
storms – mix up the atmosphere
strong winds
higher sun angles
colder air moving over valleys with cold air trapped.
Each of these statements is false – explain why.
6. Inversions only form during the winter months.
Inversions can form anytime of the year and actually form most mornings. Strong inversions tend to form during the
winter months because of the low sun angle which keeps the ground from warming up. In the summer, the sun is high in
the sky and can easily heat up the ground causing morning inversions to disperse.
7. Without pollution from cars, industries, and homes, inversions would not form.
Inversions form all over the world regardless if anybody lives in that area or not. Pollution does not cause inversions.
Atmospheric conditions cause inversions.
8. Inversions indicate bad air quality.
Remember, inversions are not pollution! However, if you live in an urban area, especially within a valley location, and a
strong inversion forms, pollution will get trapped with the cold air and air quality will decrease.
9. Inversions are a hazy white or brown color.
Again, inversions are colorless and odorless because they are not pollution. Inversions are a change in how the
temperature changes as you go up in the atmosphere. Pollution is what causes the hazy skies.