Download Investigating Weather

Investigating
Weather
Teacher’s Guide
Produced by
Colgren Communications
Written by:
John Colgren
Footage:
Gene Rhoden
Grant Goodge
Robert Prentice
Roy Britt
Published and Distributed by
AGC/UNITED LEARNING
1560 Sherman Avenue
Suite 100
Evanston, IL 60201
800-323-9084
24 Hour Fax No. 847-328-6706
www.agcunitedlearning.com
e-mail: [email protected]
INVESTIGATING WEATHER
Viewing Time: 17 minutes
INTRODUCTION
This video is designed for use in grades 1 through 4 as an introduction
to the major ideas and concepts associated with the study of our planet’s
weather. Students will learn about the water cycle, the atmosphere,
the tilt of the earth, the reason for seasons, wind, air pressure, air movement, different violent storms, and the job of meteorologists.
PROGRAM OBJECTIVES
After viewing the video and participating in the lesson activities, the
students should be able to ...
• Recognize how weather influences our lives.
• Discuss how air masses form over different regions and take on characteristics of those regions.
• Describe the water cycle.
SUMMARY OF THE VIDEO
The weather happens in the lowest layer of our atmosphere called the
troposphere. Weather happens because of the energy given off by the
sun. The sun’s energy drives the earth’s weather and keeps the water
cycle going.
The tilt of the earth’s axis is responsible for our different seasons. When
the Northern Hemisphere is tilted towards the sun, that area of the
planet is having summer. During that time, the Southern Hemisphere
is tilted away from the sun, so that area is having winter.
Air masses form over different parts of the planet. These air masses
will have different amounts of moisture content, depending on whether
they form over land or water. Over the water the air masses collect a
lot of moisture. Over land the air masses collect little moisture and are
considered dry. These air masses move from one place to another because of changes in pressure.
The land and water heat up differently, and because of the angle of
rays of sunlight, different places receive varying amounts of heat energy. The heat absorbed by the land or water causes the air above to be
warmed or cooled. Warm air rises, and as it does so, cool air rushes in
to replace it. This causes winds and helps with the circulation of air
masses.
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TEACHER PREPARATION
Before presenting this lesson to your students, we suggest that you
preview the video and review this guide and the accompanying blackline masters in order to familiarize yourself with their content. Duplicate the blackline masters you intend to use. See page 3 for a description of the blackline masters. An answer key is provided on page 4.
As you review this guide and the blackline masters that accompany it,
you may find it necessary to make some changes, additions or deletions to meet the specific needs of your class. We encourage you to do
so, for only by tailoring this program to your students will they obtain
the maximum instructional benefits afforded by the material.
It is also suggested that the video presentation take place before the
entire class and under your direction. The lesson activities grow out of
the content of the video; therefore, the presentation should be a common experience for all students.
INTRODUCING THE VIDEO
Everyone is affected by weather everyday. In fact, one of the first decisions we make everyday is how to dress. This decision is usually
based on current or predicted weather conditions. Weather is constantly
changing and moves from one place to another. Some planets would
experience very little change in their weather but our planet’s weather
can vary from very cold, snowy conditions to toasty warm, sunny days.
Ask students to discuss their favorite seasons. Why do they like that
time of the year the most? How many other people like that season?
Present the video. The viewing time is 17 minutes.
FOLLOW-UP DISCUSSION
• One of the most important topics discussed in the video is the finite
amount of water on earth. Go over the demonstration presented in the
tape. Even though three-fourths of the surface of the planet is covered
by water, only a small amount of this water is suitable for drinking
and growing plants. There is a very small percentage of fresh water on
our planet. Students should understand the importance of protecting
our supply of fresh water and making sure that the water cycle functions properly.
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• Discuss with the class why our planet has seasons. Mention the
earth’s tilt and possibly illustrate this by moving a globe around a student who is holding a flashlight. Remind students that when we are
having winter, the Southern Hemisphere is having summer.
• Repeat the question given in the introduction to the video. Ask
students again to discuss their favorite seasons and what is special
about each one. The follow-up activity entitled, “The Seasons” could
be a kick off point for listing the best about each season. A variation
might be to discuss the hardships or problems associated with each
season.
FOLLOW-UP ACTIVITIES
Some of the blackline master activities have been developed for grades
1 and 2 and some for grades 3 and 4. Choose the ones most appropriate for your students.
• The Beaufort Wind Scale provides an explanation of the Beaufort
Wind Scale and shows how it uses the observation of common objects
to estimate wind speed.
• The Beaufort Wind Scale, Page 2 is to be used by students to record
a week’s worth of data concerning wind speed. Students should use
page 1 to help determine an estimate of wind speed for the same time
period each day for a week.
• Making a Homemade Barometer gives directions for making a barometer from some simple household objects.
• Homemade Water Cycle is a simple-to-make demonstration of the
water cycle.
• The Heating of Land and Water is an experiment for testing whether
soil or water will heat up the most when exposed to the sun’s energy
over a period of time.
• Slanted Rays is an experiment that illustrates how the slant of the
rays of sunlight will affect the amount of energy that a specific area of
the earth receives.
• Snowflakes is an experiment for observing snowflakes up close.
Snowflakes won’t last long so the students need to make their observations outside with magnifying lenses.
• Homemade Snowflakes gives directions for making snowflakes cut
from construction paper.
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• The Water Cycle is a diagram of the water cycle. Students are to fill
in the missing phrases.
• The Seasons is a writing assignment about the four seasons. Students are to write about their favorite things to do during each of the
four seasons. This should be done on a separate sheet of paper.
• Quiz has eight questions about the topic of weather. You may choose
this quiz or develop one of your own.
ANSWER KEY
THE BEAUFORT WIND SCALE is a reference sheet.
THE BEAUFORT WIND SCALE, PAGE 2 should be filled in by each
student. It will include the day, temperature, a description of the cloud
cover, wind speed, and a description of how the wind speed was determined.
MAKING A HOMEMADE BAROMETER requires students to build
a working barometer. It will be interesting to compare results that
each student records.
HOMEMADE WATER CYCLE will demonstrate how water can evaporate and then return to liquid form. Water droplets should be observed
on the underside of the plastic wrap after a few hours of sitting in the
sun. The sun’s energy will evaporate some of the water and change it
to water vapor which will be invisible. After it touches the plastic wrap,
it should condense back to liquid form as droplets. To speed up the
condensation, one or two ice cubes or could be placed on the plastic
wrap.
THE HEATING OF LAND AND WATER should show that soil heats
up faster than water. The temperature of the soil should be higher
than the temperature of the water.
SLANTED RAYS is an experiment which should show that as the flashlight rays spread out, they cover more graph paper squares. The idea
here is that the more squares affected, the less energy an individual
square would receive. So the rays that are straight on will be the most
concentrated and affect the least number of squares.
SNOWFLAKES is an experiment that must be done outside on a snowy
day. The students are to capture snowflakes on the black paper and
then quickly look at them with the magnifying lens. Snowflakes have
six sides but are all different.
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HOMEMADE SNOWFLAKES provides directions for cutting snow
flakes out of construction paper.
THE WATER CYCLE
A = sun heats water
B = water vapor rises
C = clouds form
D = precipitation
THE SEASONS
Answers will vary for this writing assignment.
QUIZ
1. B
2. A
3. a,b,and c will vary.
4. Sea breezes happen because land and water heat up at different
speeds. The land heats up faster than water, so the air above the land
is heated and rises. The cooler air over the water comes in to replace
the warm air that has risen. At night, the breeze goes the other direction because the water holds the heat energy better than the land, so
the air above the water rises and cool air over the land moves in to
replace it.
5. The energy from the sun heats water and changes some of it to
water vapor which rises into the atmosphere. As the water vapor rises,
it becomes cooler and cooler until it may start to condense and form
clouds. If cooling continues, the water vapor may return to the earth
as precipitation.
6. The water cycle is critical to life on earth. There is a finite amount of
fresh water on the earth and in the atmosphere. To keep this supply of
fresh water circulating, nature recycles. If this delicate cycle were
changed or disturbed, then life on our planet would be threatened. Every living thing needs water for survival.
7. black
8. water vapor
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SCRIPT OF VIDEO NARRATION
INVESTIGATING WEATHER
What is responsible for hurricanes, tornadoes, winds, thunderstorms,
rain, snow, and all the other kinds of weather we experience here on
earth? Believe it or not, it is something very far away from our planet.
In fact, it is at the center of our solar system and is called our sun. The
energy from the sun powers the weather that we have on earth.
Our planet is surrounded by an atmosphere of gases that extends hundreds of miles above the surface of earth. This atmosphere is made up
of gases, liquids, and even very small particles of solids, such as dust
and dirt. The atmosphere is thickest in the lowest level called the troposphere. This is where all our weather occurs.
The energy from the sun travels through space an incredible 93 million
miles to reach our atmosphere. Some of the energy is blocked by the
atmosphere when it hits dust and water particles. This energy bounces
back into space.
Most of the invisible ultraviolet waves of energy that can harm plants
and animals are absorbed by the protective ozone layer that surrounds
our planet. These ultraviolet rays are very harmful, and in space, our
astronauts have to wear special space suits to protect themselves because they are away from the protection of our atmosphere.
Part of the sun’s energy reaches the earth and is reflected, or bounces
back to space. Some of the energy isn’t reflected but instead is absorbed by the soil and water.
Things that are dark in color easily absorb, or soak in the heat energy.
Things that are light colored don’t absorb as much heat—they reflect it
away. Here is a simple demonstration of that idea.
Here are two different containers. One is painted white and the other
is painted black. Water is poured into each container and a thermometer is used to record the temperature. After the cans have had a chance
to sit in the sun for awhile, the temperature is read again. The dark can
has absorbed more heat energy because its temperature has increased
the most.
The earth absorbs the heat energy from the sun and heats the air above
it. Different parts of the planet absorb different amounts of heat energy.
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The polar regions reflect a lot of energy because of all the white snow,
while other places absorb much of the heat that reaches them.
When the air above the surface is heated, it expands and rises. Warm
air is lighter than cold air and so it rises. That’s why these balloonists
use big burners to heat the air inside the balloons to make them light
enough to float in the air.
As air is heated, the molecules that make up the air spread apart and
take up more room than cooler air. There are less air molecules inside
the balloon, so it floats in the surrounding cooler air.
So air above warm surfaces of the earth is heated and rises. As it rises,
cooler air comes in to replace it. This is what causes air movements we
call wind.
How much the surface of the earth heats up depends on how many
hours of sunlight the area receives and the angle of the rays from the
sun.
The earth is tilted on its axis. This tilt is responsible for our seasons
and the difference in temperatures. The earth stays tilted at about 23.5
degrees.
As our planet goes around the sun, it is sometimes tilted in such a way
that the Northern Hemisphere is tilted away from the sun and the
Southern Hemisphere is tilted towards the sun. During that time, our
country is having winter and countries in South America are having
summer.
At other times of the year the reverse occurs and we have summer and
the Southern Hemisphere has winter.
During winter, the angle of the sun’s rays are greater than during summer when the rays are more straight on. We can illustrate this idea
with graph paper and a flashlight. We’ll pretend the flashlight is the
sun and the light from the flashlight are rays of sunlight. When the
light strikes the graph paper from straight on, the light strikes only a
small area of the paper. When the flashlight is at an angle the light
spreads out over a larger area. When it spreads out, it has less effect on
any given point.
The same thing happens when rays of sunlight strike our planet. The
area at the equator receives rays that are more direct and therefore,
temperatures in this area are warm throughout the year.
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At other places, the angle of the rays depends on what time of year it is
and whether the earth is tilted away or towards the sun. Actually,
during summer for the United States, the earth is farther away from
the sun than during winter. What determines the seasons is the tilt of
the earth as it orbits the sun.
Water is very important to the workings of the atmosphere. On earth
we have a certain amount of water. It is recycled in a complex system
called the water cycle.
Energy from the sun heats the water in the oceans, lakes, and soil causing some of it to evaporate. This means the water changes from its
liquid form into a gaseous form called water vapor. This water vapor
rises into the atmosphere. As the water vapor rises in the atmosphere,
it becomes cooler and begins to change back into a liquid form.
Clouds form and if the cooling continues, the water vapor may condense into water droplets or ice crystals. As the cooling continues, the
water returns to the earth as precipitation. This may be in the form of
rain, sleet, hail or snow.
Even though three-fourths of our planet is covered by water, only three
percent of this water is fresh water.
Let’s pretend that all the earth’s water is represented by the water in
this one-liter flask. One liter is equal to 1000 milliliters. Out of that
1000 milliliters, 972 milliliters is salt water in the oceans. We can’t drink
that water or use it to grow crops. That leaves 28 milliliters as fresh
water. However, 23 milliliters of that fresh water is found as ice and 4
milliliters as underground fresh water. Out of all that water, only 2
drops from this medicine dropper represent the amount of fresh water
in lakes and ponds. Only a very small drop shows the amount of fresh
water in the soil and air.
When water evaporates, it is clean and fresh because only the water
vapor rises into the atmosphere; other particles, such as salts and dirt,
are too heavy to evaporate.
This cycle has been operating for billions of years and is necessary to
keep our planet’s supply of fresh water continuing. You can probably
see that even though the earth is covered with water, only a small part
can be used for drinking and growing plants. It is important that humans don’t do anything that changes this life-supporting cycle we call
the water cycle.
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Now let's look at how weather moves from one place to another. Meteorologists are scientists who watch weather closely and try to determine what the weather will be like in a certain area.
Weather conditions change from day to day because of the movement
of air masses. An air mass is a large body of air that forms over a
certain area of our planet. It may form over land or water, or maybe it
will form over cold areas up north or warm areas near the equator.
The air mass takes on the characteristics of the area it forms over. This
means that air masses forming over water are moist, while air masses
forming over land are dry. Air masses forming over cold polar regions
are cold, while air masses forming over the tropics are warm.
Air masses move from one place to another because the earth isn’t
heated equally. Remember that our planet is tilted on its axis. Because
of this tilt, the sun’s rays strike the earth at different angles and therefore, the earth is heated unevenly.
Warm air rises when it is heated creating low pressure. Cold air masses
have high pressure because there is more air in a given spot in cold air
masses.
If we could see the air molecules in a column of warm air and a column of cold air, we would see that the cold air column has more molecules. That’s because when air is heated, the molecules spread out.
The cold air mass moves into areas of low pressure and air movement
results.
On a weather map we can identify air masses by the capital H for high
pressure and the capital L for low pressure. Weather forecasters and
meteorologists can predict the weather for an area of the world by looking at the movement of air masses.
You may have felt this movement of air while at the beach. The land
heats up faster than the water so the air above the beach rises and the
cooler air above the water moves in to replace it. We feel a cooling
breeze from the water. At night the opposite happens. The water holds
onto the heat longer, so the air above the water rises and colder air
above the land moves out to the water.
As air masses meet, a boundary between them forms. The air masses
don’t mix but one pushes the other along. These boundaries are called
fronts.
A cold front forms when a cold air mass pushes a warm air mass. The
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cold air is denser than the warm air and causes the warm air to rise
quickly. As the warm air rises, the moisture it contains begins to cool
and condense. The water vapor in the air changes to liquid droplets
and clouds form.
Thunderstorms may form because of this action. Thunderstorms are
violent storms capable of much destruction from high winds and lightning. At any given moment, there are about 2000 thunderstorms occurring around the world. Thunderstorms usually don’t last very long
but they can be a real threat to people and property.
Lightning which often occurs during thunderstorms can be very dangerous. You must remember to seek shelter inside a building. Don’t
go under a tree. Try not to be the tallest thing around. Get out of the
water and away from a pool or beach.
Large thunderstorms, called super cells, may spin out a series of tornadoes. These are very violent, localized storms that can have winds as
high as 300 miles per hour. Winds from a tornado can lift railroad cars
or automobiles, rip boards and roofs from buildings, or uproot trees.
Most tornadoes last only a few minutes, but there have been monster
tornadoes that have lasted for hours and traveled 200 miles on the
ground.
Tornadoes may be tops when it comes to wind speed, but in terms of
overall damage potential and shear power, hurricanes, typhoons, and
cyclones have everything else beat. These are storms that form over
the warm waters of the tropics. These storms are given different names
in different parts of the world as shown on this map.
Tornadoes have stronger winds but only effect a small region and usually last only a few minutes. A hurricane has winds of more than 74
miles per hour but will stretch over an area of more than a 100 miles.
Also hurricanes can last as long as a week. Besides high winds and
rain, flooding also is a problem with hurricanes.
Hurricanes form in tropic oceans where the water temperature is at
least 80 degrees. The hurricane is made up of many thunderstorms
that begin to circle around a central area. This central area is quite
unusual because it remains an area in the center of this massive storm
that is completely calm. It is called the eye of the hurricane. You can
see hurricanes clearly when looking at satellite photos.
This meteorologist has used information given to him by computers
hooked to weather stations around the country to prepare a weather
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report for his viewers. He must look at weather maps and study conditions in different places to make a forecast for the area he lives in. He
prepares maps and charts to help explain what he thinks will happen
over the next few days. When he gives his weather forecast, he stands
in front of a green screen that can be made to show the maps and charts
he prepared earlier. This way he can point to things and areas of interest.
Weather is important for everyone. We need to know how the weather
might change so that we can dress properly and make careful plans for
how our day will be spent. Listening to weather forecasts on television or on the radio is a good way to start your day.
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