Principles of Weather
Fronts and Air Masses
Seasons
Climate
Grab Bag
100
What is humidity?
Humidity is the amount of water vapor in the air.
100
What is an air mass?
A large body of air with relatively consistent temperature and humidity.
100
What is the difference between direct and indirect light?
Direct light is more concentrated and has more energy in a given area. Indirect light strikes at an angle, is less concentrated, and has less energy in a given area.
100
How are weather and climate different?
Weather talks about what's happening right now--it's short term. Climate talks about patterns or averages over a long period of time.
100
How does elevation affect temperature?
As elevation rises/increases, temperature decreases. There is less atmosphere to trap the heat in, and you are farther away from the ground which radiates heat.
200
Describe what a high pressure air mass would look like on the molecular level.
There would be a high density of molecules and they would move quickly. This would result in many collisions.
200
What is the difference between a front and an air mass?
An air mass is a body of air. A front is the boundary between two separate air masses.
200
When Ms. Leist went to visit her friend in Australia a few years ago, she chose to go over Christmas because it would be summer there. Why would Australia have summer when we have winter in Boston?
When the northern hemisphere is tilted away from the sun, that means that the southern hemisphere is tilted toward the sun, so it is summer in the southern hemisphere.
200
How does a region's latitude affect its climate? Explain.
At the equator, you would expect a warm climate because the region gets direct light from the sun all year round. As you get farther from the equator and closer to the poles, light becomes more and more indirect, and the climate gets cooler.
200
What is a dew point?
The dew point is the temperature where water vapor will condense into water in a given air mass.
300
Would you expect clouds to form more readily over the ocean or desert? Why?
Over the ocean--more water would be able to evaporate, which would result in higher humidity and more cloud formation.
300
Draw a model that shows what happens at a warm front. Your model should be clearly labeled!
The warm air mass bumps into the cold air mass, rising above it because it is less dense.
300
Would we expect to see a change in the seasons if the Earth was no longer tilted?
There would be no seasons if there Earth wasn't tilted!
300
How does evaporation redistribute heat?
A lot of energy goes into changing water from liquid to gas. That water vapor can then travel somewhere else. When it condenses, that energy is released into a new environment.
300
When you look at the weather forecast for Seattle, you see that there is a temperature of 51 degrees and humidity of 90%. The pressure is dropping. What sort of weather would you expect to experience in Seattle today and why?
It's probably going to be rainy--there's low pressure, which forms clouds, and high humidity, so there's a lot of water vapor in the air. It will be rain and not snow because of the temperature.
400
In what direction does wind travel? Explain.
Wind travels from high pressure to low pressure. This is because air molecules want to equilibrate their pressure, so they will travel to a low-pressure area where they have more space.
400
The temperature drops suddenly, and you see dark clouds on the horizon. You hear a rumble of thunder in the distance. What is happening? How do you know?
A cold front is passing through!
400
Explain why we have seasons. Be specific!
1. The Earth is tilted on its axis. This tilt means that different parts of the Earth get more or less direct light depending on the time of year. 2. When a region gets more direct light, it's summer. When a region gets less direct light, it's winter. 3. The seasons change as the Earth revolves around the sun.
400
How would you expect the climate in Boston (a coastal city) and Albany (an inland city at the same latitude) to be different? Why?
Boston's climate should be less variable--warmer winters and cooler summers--because of its location near the ocean. The ocean warms and cools slowly, meaning the land around it also warms and cools slowly.
400
What sort of weather conditions might you expect if a cold front passed through Boston in the middle of January?
Temperature would get REALLY cold, there would be some precipitation--probably snow, because of the cold temperature--and the snow would be heavy but end quickly.
500
Describe how a cloud is formed. Be specific!
1. Water evaporates, turning into water vapor that becomes part of an air mass. 2. The air mass is heated by the ground, causing it to become less dense and rise. 3. When the air mass has risen to the point where the temperature is equal to dew point, the water vapor condenses and forms clouds.
500
Why do cold fronts move more quickly and bring more severe weather than warm fronts?
Because cold air masses are more dense than warm air masses, a cold front moves quickly because the denser air mass is doing the pushing. This can cause instability in the air, which can cause severe weather.
500
Why is distance NOT the reason for the seasons?
The Earth stays at approximately the same distance from the sun throughout its orbit. Even though the Earth is a little bit closer to the sun during January-February, that's winter in the Northern Hemisphere. Because the hemispheres have opposite seasons, distance can't explain why the seasons happen since the Earth is just one distance from the sun.
500
Western Europe has a much warmer, more humid climate than you would expect for a region at its latitude. Why is that the case?
The Gulf Stream current carries warm, moist air from the tropics all the way to western Europe!
500
Draw a model of a warm air mass and a cold air mass that shows how they are different.
In a warm air mass, you would see less density and faster-moving molecules. In a cold air mass, you would see more density and slower-moving molecules.
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