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Measuring Weather
How Does Sunlight Affect Air Temperature?
How does Temperature Affect Air Movement?
What Causes Clouds and Precipitation?
How Do Meteorologists Predict Weather?
Lesson 1:
How Does Sunlight Affect Air
Temperature?
• Why is it cooler at night than in the afternoon? It is because the
temperature of the air has to do with how much sunlight, or light
energy from the sun, reaches the earth.
• Sunlight passes through the air but does not heat it. Rather, light
energy from the sun hits liquids and solids on the surface of the
earth. As the liquids and solids get warm from the sun they warm
the air above them.
• The earth’s surface does not heat evenly due to sunlight hitting the
earth at different angles.
• In addition to the angles affecting temperature so does time of day
and seasons. It is usually coolest in the morning before sunrise and
warmest in the afternoon. Also, there are more hours of sunlight in
the summer than in the winter, giving the earth’s surface more time
to heat up.
Different Surfaces and Temperature
• Different surfaces absorb different amounts of light
energy. Are your feet cooler on grass or on the
sidewalk?
• For instance, the air temperature at Jones Beach is
cooler because of the breeze from the ocean. Oceans
heat up more slowly causing air temperature to be cooler
than land surfaces.
• How do you find out what the air temperature is? Air
temperature is measured by a tool called a thermometer.
• C on the thermometer stands for Celsius. Celsius is a
metric scale for measuring temperature. What is the
name of the measurement of temperature we commonly
go by?
GRASS?
SIDEWALK?
•
Lesson 2:
How Does Temperature Affect Air
Movement?
Air is made of matter and has mass. Air presses down
on the earth and us. The pressing of air is called air
pressure.
• Changes in temperature cause changes in air pressure.
As the air near the earth’s surface becomes warmer, the
particles of air move farther apart. The air becomes
lighter and rises causing less pressure on its’ surface
and us creating a low pressure area.
• Cold air is heavier than warm air. Its’ particles are much
closer together, making the air heavier, causing more
pressure on the earth and us; thus, a high pressure
area is formed.
• How do you measure air pressure? Using a tool called a
barometer will tell you the air pressure around you.
Measuring Wind Direction and
Speed
• How can you measure wind when it is invisible? If you watch things
move you can tell the direction of the wind. For a more exact
measurement of the wind scientists use a wind vane.
• A wind vane is a tool that shows wind direction. A wind vane has a
tail that is moved by the wind. On the opposite side it has an arrow
that points to the direction of the wind, whether it is north, south,
east, or west.
• A wind sock also shows wind direction, as well as wind speed. If
the wind is high the sock will stand straight out. If it is a low wind it
will barely lift up.
• For an accurate measurement of wind speed, scientists use a tool
called an anemometer. Three or four cups are attached to a pole.
As the wind pushes the cups around the wind speed is measured by
how many spins per minute.
wind vane
wind sock
anemometer
Lesson 3:
What Causes Clouds and
Precipitation?
• As we stated before warm air rises. As it
rises it cools, as it distances itself from the
earth. As it cools it becomes water vapor,
which are tiny water drops. The more and
more they gather they form a cloud.
• Since water vapor is needed to form a
cloud, you will see many clouds in places
where the air is very moist. Would you
see many clouds in a desert?
Types of Clouds
• There are three types of clouds: Stratus,
Cumulus, and Cirrus. The are very
different in shape and size.
• The Stratus clouds are the low clouds that
form flat, wide layers.
• The Cumulus clouds are dome shaped
with flat bottoms.
• The Cirrus clouds look like thin threads or
feathers arranged in bands.
Kinds of Precipitation/ Measuring
Precipitation and Humidity
• Precipitation is moisture that falls from clouds
to the ground. Rain, hail, snow, and sleet are
examples of moisture that falls to the ground.
• A rain gauge is a tool that measures rain fall. It
is an open-topped container that collects rain.
• Humidity is a measure of the amount of water
vapor in the air.
• Humidity can be measured by using a
hygrometer. A hygrometer uses a hair attached
to a pointer. As the hair absorbs water vapor
from the air, it gets longer.
rain gauge
hygrometer
Condensation-is
when water vapor
condenses and
forms clouds.
Water Cycle
Precipitationmoisture that falls
from the clouds.
Evaporation
- is when
water enters
the air as
water vapor.
Runoff-As the water falls to
the ground some of it soaks in.
The water that doesn’t runs
downhill into puddles, streams,
rivers, or lakes.
•
Lesson 4:
How Do Meteorologists Predict
Weather?
Many things cause the air to change. One of those
things is what is called air mass. Air mass is a large
body of air that has about the same temperature and
humidity throughout. Air masses can be warm or cold
and can have a little or a lot of water vapor.
• Air masses typically move from west to east (California
to New York). Sometimes as they travel they encounter
another air mass. Air masses do not blend, they stay
separated. Where two air masses meet is called a front.
• A cold front happens when a cold air mass pushes into
a warm air mass causing thunderstorms or heavy rain.
• A warm front is when a warm air mass slides slowly
over the top of a cold air mass causing light rain or snow
for several days.
Tracking and Predicting Weather
• A forecast is a prediction of what the
weather will be like for the next few days.
• A weather forecast is made by a
meteorologist-a person who studies the
weather.
• Many meteorologist get their information
from the National Weather Service. This
government agency has weather stations
all over the United States.