Predicting the Weather
By Phyllis Naegeli
1
Swirling winds, fluffy clouds, driving rain, falling snow, sleet, hail, fog, and rolling thunder
are all a part of our day-to-day lives. But how do we find out what our weather is going to do?
Predicting the weather is the job of meteorologists, specially trained people who study the
earth's atmosphere.
2
The atmosphere is a layer of air surrounding our earth. All of our weather happens in the
bottom layer of the atmosphere, called the troposphere. Here, air masses move around the
globe, causing changes in the weather. Air masses are large pockets of air that have the same
pressure and amount of moisture. As the sun warms the surface of the earth, air masses are
heated. As these air masses rise, they cool down. Moisture plays a big part in determining the
weather they bring. If the air has no moisture, it brings dry weather. However, if an air mass
contains lots of moisture, it can bring heavy rains or snow.
3
Weather people gather information from many different sources. Barometers measure air
pressure. Anemometers measure wind speed and direction. Meteorologists use thermometers to
measure temperature. They measure humidity with a hygrometer. Rain and snow amounts are
measured and recorded. All this information is fed into a computer to let meteorologists know
what is happening in our atmosphere.
4
Meteorologists spend many hours each day gathering information and watching for
developing weather systems. They draw maps with lines called isobars. You may have seen these
on the weather maps shown on the evening news. Each isobar connects areas of equal pressure.
In the center of an area of pressure, they place an "L" for low pressure or an "H" for high
pressure. Low pressure brings stormy weather, while high pressure brings calmer days. The
differences in high and low air pressure causes wind. The greater the difference in pressure
between a high and low pressure air mass, the stronger the winds will be.
5
Weather also follows patterns. Meteorologists use historical data to help them determine
the chance of certain weather on any given day. If the same type of information is found to
have produced rain fifty-percent of the time, then you will see the chance of rain listed as fifty
percent. Certain types of conditions help to predict thunderstorms, balmy days, hurricanes, and
snowstorms.
6
You can be a meteorologist by keeping track of weather patterns over a period of time.
Record temperature, wind, rainfall amounts, and areas of high and low pressure. You can make
your own measuring instruments or use a weather station to help you record this information.
Put together a form to keep track of the information you gather. Before long, you'll be able to
write your own weather forecast.
Name _____________________________
Date ___________________
Predicting the Weather
1.
A large pocket of air that has the same
2.
Which instrument measures air pressure:
pressure and amount of moisture is called
Rain gauge
a(n)_____________________.
Anemometer
Barometer
Weather vane
3.
What is an isobar?
4.
Weather never follows patterns.
False
True
5.
High pressure brings what type of
6.
weather?
7.
Low pressure brings which type of
weather?
Calmer
Dull
Stormy
Stormy
Winter
Winter
Freezing
Balmy
Name two instruments that
meteorologists use to measure the
weather. Bonus: Tell what information is
gathered from the instruments.
8.
What is the name of the layer in our
atmosphere where our weather occurs?