NAME _______________________________
DATE______________
PARTNER(S)_________________________
PREDICTING THE WEATHER
How well does your local weatherman do in predicting the weather? Is he or she more accurate
for the next day or for a week in the future?
Why do you think that it is hard to make very accurate forecasts?
List the variables (like temperature) that you think play a part in the weather in a given region for
a particular time.
Let’s Explore!
To investigate weather prediction we will be using some activities from the Internet.
1.
Locate yourself at a computer with Internet access and launch a browser such as Internet
Explorer or Netscape.
2.
Go to the following URL:
http://vathena.arc.nasa.gov/curric/weather/hsweathr/index.html
3.
After reading through and working on the “Predicting the Weather” page work through
Lessons 1-3. The pages and maps you need as you go along are reproduced with this
activity. Use colored pencils as needed.
NOTE:
The following pages have been reproduced with minor modifications for
educational use only from:
http://vathena.arc.nasa.gov/curric/weather/hsweathr/index.html
Explorations in Earth and Space Science
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PREDICTING
THE WEATHER
Red sky in
morning,
sailors
give
warning.
red sky at
night,
sailors
delight.
What does the rhyme mean? It was used by sailors in the United States for many
years. Is this old saying true?
As a matter of fact, the saying often holds true in the United States. Because the
weather patterns in North America generally move from west to east, when clouds
arrive overhead at sunrise the sky will appear red, signaling a storm "moving in".
When the storm eventually passes, the sky will clear in the western sky. If sunset
occurs simultaneously, the light will cast a red glow on the clouds above, now
moving towards the east.
Sample Four-day forecast
View a current four day forecast for your
city.
This modern, four day weather forecast,
obviously relies on more than simply the
current observations of the sky. What are
the factors that help meteorologists make
this forecast? What methods were used to
make the predictions?
Weather forecasting is not an exact
science. It ranges from weather folktale
simplicity to elaborate computer
simulations that rely on a variety of
methods to produce their results.
Our focus will be to use common surface level data, as shown on most local TV
weather maps, to understand weather patterns. After practice in reading
weather maps, you will make maps predicting the weather for the next few days
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across the country. You can then compare your maps with the "experts" and the
real weather as it occurs.
Activities (Lessons)
•
•
•
LESSON 1: ISOBARS
LESSON 2: ISOTHERMS
LESSON 3: FRONTS
Other Information
•
•
•
•
•
Weather Data Collection Methods
Weather Folktales
Glossary from The Weather Channel
Related Links
Teacher Talk
Image Credits:
Forecast from http://www.intellicast.com/.
Maps from The Weather Channel
Red sky photo from National Weather Service.
•
An example of NWS services: Interactive Marine Observations
Written by: Gene Rempel and Mike Hanson
Last Modified September 19, 1998
Explorations in Earth and Space Science
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LESSON 1: ISOBARS
What's the difference between a High and a Low?
What kinds of weather are likely to be found in each?
Certain weather maps allow
us to view High and Low
pressure systems that control
the weather. An isobar is a
line connecting locations of
equal barometric pressure.
Isobar maps show where
pressures are relatively high
and low, and show us where
pressure changes are gradual
or dramatic over a distance.
Exercise 1:
•
This activity will assist you in creating and interpreting weather maps with isobars.
•
The image above shows an example of a weather map containing isobars. The thick black
lines are called isobars. They are typically placed at intervals of 4 millibars.
Select Image 1 and print out the map with pressure readings.
1. Determine which 4 millibar intervals will be necessary to use for this map. (Keep in mind
that the isobars are found every 4 millibars such as 996, 1000, 1004, etc.)
2. Draw in the isobars on the map you have printed out. Start with the 1000 mb line, then
adding 996 mb, 1004 mb, etc. Label each isobar. Note: isobars form sets of curves that do not
cross each other.
Isobars can be used to identify "Highs" and "Lows". The pressure in a high is greater than the
surrounding air. The pressure in a low is lower than the surrounding air.
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3. Label with an "H" the center of a high pressure area.
4. Label with an "L" the center of a low pressure area.
High pressure regions are usually associated with dry weather because as the air sinks it warms
and the moisture evaporates. Low pressure regions usually bring precipitation because when the
air rises it cools and the water vapor condenses.
5. Over which state would you expect to see rain or snow?
6. Over which state would you expect to see clear skies?
In the northern hemisphere the wind blows clockwise around centers of high pressure. The wind
blows counterclockwise around lows. It is the opposite in the southern hemisphere.
7. Draw arrows around the "H" on your map to indicate the wind direction.
8. Draw arrows around the "L" on your map to indicate the wind direction.
Imagine that you live in El Paso, TX.
9. If a High were approaching you from the west, describe the shift in wind direction as the High
approaches you and then passes to the east.
10. How would pressure measurements change as the High approaches and then passes to the
east?
Imagine that you live in New York City.
11. If a Low were approaching you from the west, describe the shift in wind direction as the
Low approaches you and then passes to the east.
The strength of the wind is determined by differences in the pressure, the pressure gradient. A
large change in pressure over a short distance would indicate strong winds. On a weather map,
isobars that are close together indicate a strong pressure gradient.
12. Indicate on your map where you expect the strongest winds (the steepest pressure gradient).
Explorations in Earth and Space Science
PSC 121
Prince George’s Community College 155
Image Credits:
Maps from The Weather Channel
Maps from Tiger Census Maps
Written by: Gene Rempel and Mike Hanson
Last Modified September 19, 1998
LESSON 2: ISOTHERMS
Will it be warm outside tomorrow?
Certain weather maps allow us to view warm and cold areas in an easy fashion. One
helpful weather map contains
isotherms. An isotherm is a line
connecting locations with equal
temperature. Isotherm maps show
where temperatures are relatively
high and low, and also where
temperature changes are gradual or
dramatic over a distance.
This image shows an example of a
weather map containing 60° and 70°
isotherms. The large black lines are
called isotherms. They are typically
placed at intervals of 10 degrees
Fahrenheit.
Exercise 2:
•
This activity will assist you in creating and interpreting weather maps with isotherms.
Select Image 2 and print out the map with temperature readings.
1. Determine which 10 degree intervals will be necessary to use for this map.
2. Draw in the isotherms on the map you have printed out. Label each isotherm.
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Isotherms can be used to identify air masses (large areas of the lower atmosphere with similar
weather). Air masses are generally referred to as cold or warm. Cold air masses are colder in the
center, and warm air masses are warmer in the center.
3. Name a state over which a cold air mass is located.
________________________
4. Name a state over which a warm air mass is located.
________________________
Air masses are also categorized as dry or humid. Humid air masses develop over ocean waters.
Dry air masses come from large land areas. An air mass found over the Gulf of Mexico would be
humid and warm. An air mass located in central Canada in winter would be dry and cold.
5. How would you describe the air mass moving into the United States from Canada?
Activities (Lessons)
•
•
•
•
•
•
LESSON 1: ISOBARS
LESSON 2: ISOTHERMS
LESSON 3: FRONTS
LESSON 4: WEATHER PREDICTION
LESSON 5: WEATHER PATTERNS
LESSON 6: WEATHER PROVERBS Part A and Part B
Other Information
•
•
•
•
•
Weather Data Collection Methods
Weather Folktales
Glossary from The Weather Channel
Weather Links
Teacher Talk
Image Credits:
Maps from The Weather Channel
Maps from Tiger Census Maps
Written by: Gene Rempel and Mike Hanson
Tell us what you think about this page.
Last Modified September 19, 1998
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LESSON 3: FRONTS
What happens along cold fronts and warm fronts?
The boundary between two air
masses is called a front. As a
result, moving fronts indicate a
change in the weather. On a
weather map fronts are drawn
where there is large change in
temperature and a shift in wind
direction. A front can also be
described as the boundary
between adjacent Highs with
different conditions.
On a weather map, fair
weather is generally associated
with Highs while stormy
weather is associated with Lows and with the portions of fronts that extend from
them. Highs and Lows are usually hundreds or thousands of miles across. Both Highs
and Lows tend to travel from west to east across the United States, bringing changing
weather as they move.
The image above shows an example of a weather map containing a warm and cold
front. A cold front means a cold air mass is pushing into a warmer air mass, and is
shown with blue sharp "teeth" pointing the direction of the moving cold air. A warm
front means a warm air mass is pushing into a colder air mass, and is shown with red
rounded "teeth" pointing the direction of the moving warm air.
Exercise 3:
•
This activity will assist you in interpreting weather maps on which fronts are
already identified.
Use the map above to complete the following activity.
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Imagine that you are located at El Paso, Texas on the map.
1. As the cold front approaches, what changes in the sky condition do you expect?
2. What changes in wind direction will occur as the front passes?
3. At the time the front passes what change in temperature will occur?
Imagine that you are located at New York City, New York on the map.
4. What changes will occur in the sky condition prior to the arrival of the warm front?
5. As the warm front passes, what changes do you expect in wind direction?
6. After the front passes, what changes in weather do you predict?
The rainfall is usually different along cold fronts and warm fronts. Along cold fronts, the air is
pushed up rapidly and the front quickly passes. The rain is often more stormy and relatively
brief. Along warm fronts, the air is pushed more slowly over the cold air mass. The rainfall is
usually more gentle and extended in duration.
7. Over which city, New York or El Paso, are thundershowers more likely to occur? Why?
8. Fill in the characteristics of High pressure and Low pressure systems in the table below.
Characteristic
HIGH
LOW
Pressure
Surface Winds
Sky Conditions
Explorations in Earth and Space Science
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Other Information
•
•
•
•
•
Weather Data Collection Methods
Weather Folktales
Glossary from The Weather Channel
Weather Links
Teacher Talk
Image Credits:
Maps from The Weather Channel
Maps from Tiger Census Maps
Written by: Gene Rempel and Mike Hanson
Last Modified September 19, 1998
Activity: Weather Prediction
Now it’s time to see if you can use the information you learned to make weather predictions.
1. Your group will be given two sets of weather maps for three days. A specific location will be
identified with each set. From these complete the chart at the end of this activity for the first
three days. Then predict the weather for the next two days for the specified locations.
2. The weather maps for the next two days are available. When you have made the predictions
compare your predictions to the maps. How well did you do? Explain.
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Image 1
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Image 2
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City_____________________
Date
Actual weather
Dates____________________
Predicted Weather
Explorations in Earth and Space Science
PSC 121
Explanation for Weather
Prince George’s Community College 165
City_____________________
Date
166
Actual weather
Dates____________________
Predicted Weather
Explorations in Earth and Space Science
PSC 121
Explanation for Weather
Prince George’s Community College