Download 4 Forecasting Weather

Name
CHAPTER 16
Class
Date
Understanding Weather
SECTION
4 Forecasting Weather
National Science
Education Standards
BEFORE YOU READ
After you read this section, you should be able to answer
these questions:
ES 1i, 1j
• What instruments are used to forecast weather?
• How do you read a weather map?
What Is a Weather Forecast?
Weather affects how you dress and how you plan your
day. Severe weather can put people in danger. Therefore,
accurate weather forecasts are important. A weather
forecast is a prediction of weather conditions over the
next few days. Meteorologists make weather forecasts
using information on atmospheric conditions.
Meteorologists use special instruments to collect data.
Some of these instruments are far above the ground. Others
are tools you may be familiar with from everyday use.
WEATHER BALLOONS
STUDY TIP
Compare As you read this
section, make a chart
comparing the different tools
that meteorologists use to
collect weather data.
READING CHECK
1. Explain What do
meteorologists use to
forecast the weather?
Weather balloons carry electronic equipment. The equipment on a weather balloon can measure weather conditions
as high as 30 km above Earth’s surface. This equipment
measures temperature, air pressure, and relative humidity.
It transmits the information to meteorologists using radio
signals. Meteorologists can track the path of the balloons to
measure wind speed and direction.
TAKE A LOOK
2. Describe How do meteorologists obtain the information from weather balloons?
Weather balloons carry equipment into the atmosphere. They use radio
signals to transmit information on weather conditions to meteorologists
on the ground.
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Understanding Weather
Name
SECTION 4
Class
Date
Forecasting Weather continued
THERMOMETERS AND BAROMETERS
Remember that air temperature and pressure can affect
the weather. Therefore, meteorologists must be able to
measure temperature and pressure accurately. They use
thermometers to measure temperature, just like you do.
They use tools called barometers to measure air pressure.
WINDSOCKS, WIND VANES, AND ANEMOMETERS
Critical Thinking
3. Infer Why is it important
for meteorologists to be able
to measure wind direction?
Meteorologists can use windsocks and wind vanes to
measure wind direction. A windsock is a cone-shaped
cloth bag that is open at both ends. The wind enters
through the wide end and leaves through the narrow end.
The wide end always points into the wind.
A wind vane is shaped like an arrow. It is attached to
a pole. The wind pushes the tail of the arrow. The vane
spins until the arrows points into the wind.
An anemometer measures wind speed. It has three
or four cups connected to a pole with spokes. The wind
pushes on the open sides of the cups. This makes them
spin on the pole. The spinning of the pole produces an
electric current, which is displayed on a dial. The faster
the wind speed, the stronger the electric current, and the
further the dial moves.
Meteorologists use
anemometers to
measure wind speed.
TAKE A LOOK
4. Identify What is an
anemometer?
RADAR AND SATELLITES
READING CHECK
5. Describe Give two things
that meteorologists can use
radar to do.
Scientists use radar to locate fronts and air masses.
Radar can locate a weather system and show the direction
it is moving. It can show how much precipitation is falling,
and what kind of precipitation it is. Most television stations
use radar to give information about weather systems.
Weather satellites orbiting Earth produce images of
weather systems. Satellites can also measure wind speeds,
humidity, and temperatures from different altitudes.
Meteorologists use weather satellites to track storms.
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Understanding Weather
Name
Class
SECTION 4
Date
Forecasting Weather continued
What Are Weather Maps?
In the United States, two main groups of scientists
collect weather data. One group is the National Weather
Service (NWS). The other group is the National Oceanic
and Atmospheric Administration (NOAA). These groups
gather information from about 1,000 weather stations
across the United States to produce weather maps.
READING A WEATHER MAP
Some weather maps contain station models. A station
model is a symbol that shows the weather at a certain
location. Station models look like circles with numbers
and symbols around them. The numbers and symbols
stand for different measurements, as shown below.
$IFFERENTSYMBOLSREPRESENT
DIFFERENTKINDSOFPRECIPITATION 4EMPERATUREŽ&
&OREXAMPLETWODOTSMEANS
LIGHTRAIN
$EWPOINTTEMPERATUREŽ&
4HEMARKINGSONTHE
ENDOFTHISBARINDICATE
WINDSPEED4HEMORE
BARSTHEREARETHEFASTER
THEWINDSPEED
4HEWAYTHISCIRCLEISFILLEDIN
SHOWSTHECLOUDCOVERINTHE
AREA&OREXAMPLETHISPATTERN
INDICATESPATCHYCLOUDS
READING CHECK
6. Identify What are two
groups that collect weather
data in the United States?
TAKE A LOOK
7. Use a Model What is
the dew point temperature
for the station shown in the
figure?
4HISNUMBERREPRESENTS
THEAIRPRESSURE
4HEDIRECTIONTHATTHISBAR
POINTSSHOWSTHEWIND
DIRECTION&OREXAMPLEHERETHE
WINDISBLOWINGSOUTHWEST
8. Infer Will condensation
happen in the air at the
station in the figure? Explain
your answer.
Some weather maps, such as those you see on television, show lines called isobars. Isobars are lines that
connect points of equal air pressure. They are similar to
contour lines on a topographic map. Isobars that form
closed circles represent areas of high (H) or low (L) pressure. Weather maps also show fronts.
, EGEND
#OLDFRONT
7ARMFRONT
,OWPRESSURE
TROUGH
)SOBAR
(IGHPRESSURE
TAKE A LOOK
,OWPRESSURE
9. Read a Map On the
map, circle the areas of
high pressure.
2AIN
&OG
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Understanding Weather
Name
Class
Date
Section 4 Review
NSES
ES 1i, 1j
SECTION VOCABULARY
anemometer an instrument used to measure
wind speed
barometer an instrument that measures
atmospheric pressure
thermometer an instrument that measures and
indicates temperature
1. Compare How is an anemometer different from a windsock or a wind vane?
2. Identify What three atmospheric conditions do weather balloons measure?
3. Describe Give three things that meteorologists use weather satellites for.
4. Apply Concepts Which of the two weather stations below is experiencing higher
air temperatures? Which is experiencing higher wind speeds?
3TATION!
3TATION"
5. Apply Concepts In which direction is the wind blowing at station A? In which
direction is it blowing at station B?
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Understanding Weather
Earth Science Answer Key continued
Chapter 17 Climate
10. a rise in sea level because of a storm
11. to learn where the storm is and whether it is
SECTION 1 WHAT IS CLIMATE?
getting worse
1. temperature and precipitation
Review
1. Lightning superheats the air to produce
2.
3.
4.
5.
6.
7.
2. The sun’s energy is focused on a small area.
3. The equator receives about the same
thunder.
They can produce strong winds, tornadoes,
hail, or flash floods.
in the United States
Cold, dry air from Canada meets warm,
moist air from the Tropics, producing
thunderstorms.
Solar energy causes water to evaporate. As
it rises, cools, and condenses, it releases
the energy. Thunderstorms form, which can
combine to form hurricanes.
when they move over cooler water or land
If you are outside, stay away from tall objects
that can attract lightning. If you are in the
open, crouch down. Stay away from water.
4.
5.
6.
7.
8.
9.
10.
11.
SECTION 4 FORECASTING THE WEATHER
12.
13.
1. information on atmospheric conditions
2. The balloons transmit the data using radio
14.
3.
4.
5.
6.
7.
8.
9.
signals.
Possible answer: Wind direction can indicate
which way a weather system is moving.
a device that measures wind speed
Locate weather systems; determine how
much precipitation is being produced.
NWS, NOAA
27°F
No, because the air temperature is above the
dew point (temperature).
The three Hs on the map should be circled.
Review
1. Climate describes the average weather con-
2.
3.
4.
Review
1. An anemometer measures wind speed; wind-
2.
3.
4.
5.
amount of sunlight all year round.
differences in air pressure
west to east
Temperature decreases as elevation increases.
The air cools as it rises and drops below its
dew point.
Water absorbs and releases heat more
slowly than land, so the water helps to stabilize the temperatures on land.
The cool water absorbs heat from the
air, causing the temperature of the air to
decrease.
a warm current
latitude
tropical zone
The climate of an area affects the organisms
that live there.
along the equator
5.
socks and wind vanes measure only wind
direction.
temperature, pressure, relative humidity
tracking storms, imaging weather systems,
measuring wind speed/humidity/temperature
from different altitudes
Station A has higher air temperatures and
higher wind speeds.
Station A: southwest
Station B: north
ditions in an area over a long period of time.
Weather describes the state of the atmosphere in a specific location at a specific
point in time.
San Diego receives more sunlight because it
lies closer to the equator.
Earth is tilted on its axis of rotation, causing
some areas to receive more sunlight during
some parts of the year than during others.
latitude, large bodies of water, topography,
ocean currents, winds
Air rises to move over a mountain. The
air cools as it rises, causing the water
vapor in the air to condense into clouds.
Precipitation falls on the windward side of
the mountain, causing the area to have a wet
climate. The air rises over the mountain and
sinks. As it sinks, it gets warmer and causes
water to evaporate from the land on the
other side of the mountain. As a result, the
far side of the mountain has a dry climate.
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Earth Science