Science Test Study Guide (KEY)
Unit: Weather, Part 1
1. What are the four ways we can classify air masses and what does each term mean?
Air masses can be continental, maritime, tropical or polar. Air masses are named with
one location word and one temperature word (example: Continental polar air mass).
Continental means the air mass forms over land and maritime means it forms over
water. Tropical means the air mass forms over a warm location and is warm in
temperature, and Polar means the air mass forms over a cool location and is cool in
temperature.
2. How is wind formed?
How is wind formed? Unequal heating of the land causes air to flow from areas of
higher pressure to areas of lower pressure.
3. What has the greatest effect on wind speed?
Air pressure has the greatest effect on wind speed. The greater the difference in air
pressures between two air masses, the stronger the winds.
4. How does wind direction affect the weather?
Wind will have different temperatures and humidity levels depending on where it’s
coming from. If it is a polar wind, it will bring cooler air with it. If it’s a tropical wind,
it will bring warmer air with it. This can affect the temperatures of an area. If it is a
maritime wind, it will have higher humidity levels. If it is a continental wind, it will have
lower humidity levels. This can affect cloud and precipitation development; more
humidity equals more moisture for condensation, clouds, and precipitation.
5. What kind of weather conditions can be expected from a low pressure weather
system?
A low pressure system will bring cloudy and stormy weather.
6. What kind of weather conditions can be expected from a high pressure weather
system?
A high pressure system will bring clear, sunny weather.
7. What kind of weather conditions can be expected from a warm front? Cold front?
Stationary front?
Warm Front: As a warm air mass chases down a cold air mass and rises over the cold
air, clouds are produced along with possible steady precipitation and warmer
temperatures.
Cold Front: As a cold air mass chases down a warm air mass and sinks underneath it,
the warm air is forced to rise. It will produce clouds and possible thunderstorms along
with heavy precipitation and cooler temperatures.
Stationary Front: As a warm air mass and a cold air mass meet, neither one has the
force to move the other. As the air masses remain “standing still”, clouds or fog and
possible precipitation form and can stick around for days.
8. Define the 5 different types of precipitation.
Rain is when drops of liquid water fall to Earth’s surface. Snow is when water vapor
turns directly into ice by condensing around an ice crystal and falls to Earth’s surface.
Hail is when ice crystals freeze over and over as wind gusts push them back up into the
clouds. Sleet is a mixture of rain, snow, and raindrops that freeze on their way down.
Freezing Rain is when water droplets become super chilled and freeze upon coming into
contact with an object.
9. Describe cirrus, stratus, cumulus, nimbostratus, and cumulonimbus clouds and the
precipitation they bring.
Cirrus clouds are wispy clouds made of ice crystals, found high in the atmosphere.
They signal fair weather. Stratus clouds are gray clouds that cover the entire sky and
can have light drizzle or mist falling from them. Cumulus clouds are puffy clouds made
of water droplets, found in the middle atmosphere. They signal fair weather.
Cumulonimbus clouds are tall, stacked cumulus clouds with dark bottoms. They are
made of water droplets and found in the middle to high atmosphere. They signal
thunderstorms. Nimbostratus clouds are dark, gray clouds that produce steady rain or
snow.
10. How does cloud cover affect temperatures during the day? At night?
During the day, cloud cover keeps temperatures cooler, and at night, cloud cover keeps
temperatures warmer.
11. How do seasons differ in the northern and southern hemisphere?
In June, July, and August the Northern Hemisphere experiences summer while the
Southern Hemisphere experiences winter. In December, January, and February the
Northern Hemisphere experiences winter while the Southern Hemisphere experiences
summer. The seasons differ because of the tilt of the Earth’s rotation.