1. Investigation 6 part 5 Weather Balloons
Day 33
Investigation 6 part 5
Weather Balloons

2. WEATHER BALLOONS
Meteorologist use them to get information about the Troposphere.
A large balloon filled with helium or hydrogen.
Signals from balloon are received and recorded at a ground station.

3. WEATHER BALLOON
A small computer called a radiosonde is attached to the balloon.
The radiosonde has instruments for measuring air pressure, air temperature, relative humidity, wind speed, and direction.

4. WEATHER BALLOON VIDEO
After you watch the video be prepared to share your thoughts.

5. VIDEO DISCUSSION
Why do you think meteorologists use helium or hydrogen in their balloons?
These gases are less dense than the surrounding air, so the balloon floats up.
What do you think happens to the volume of the balloon as it rises in the atmosphere?
Surrounding air pressure decreases, so the volume of the balloon increases. Eventually it pops.

6. WEATHER BALLOON MULTIMEDIA
Watch CD-ROM Simulation
Turn to page 39 in lab book as you work with the CD- ROM.

7. PAGE 39(LB) DISCUSSION
What was the trend in air pressure as altitude increased in Chicago? In Phoenix?
Air pressure decreased in both locations. Air pressure readings were almost the same.
Describe the temperature trends in both Chicago and Phoenix.
Temperature in both locations decreases with altitude.

8. PAGE 39(LB) DISCUSSION CONT.
Was the trend the same in both cities?
Phoenix’s temperature started higher than Chicago at ground level, but it ended up lower at the highest altitude.
Which weather factors varied the most between Chicago and Phoenix?
Temperature and dew point varied the most. In Chicago the lines touched and in Phoenix they never touched.

9. PAGE 39(LB) DISCUSSION CONT.
Do you think it might be a cloudy day in Chicago? What evidence do you have?
The weather would be cloudy. The dew point and temperature were very close at a particular altitude.
At what altitude would you see clouds?
5000 to 6000 meters if condensation nuclei were present.

10. PAGE 39(LB) DISCUSSION CONT.
Do you think it might be a cloudy day in Phoenix? What evidence do you have?
The sky was probably clear with no clouds. Dew point and temperature were never the same.

11. Visualization Exercise 6.3
Reading a Line Graph
>>>next slide<<<
Visualization Exercise 6.3

12. Image: CD-Rom Exercise 6.3 Module Images: CD-ROM / online Procedure:
Image comprehension focus: Reading a line graph
Rationale: Authors may sometimes use a line graph as a way of representing certain pieces of information. Therefore, it is important that students understand how to read such graphs.
Type of Activity: Teacher Comment
Objective: To reinforce student understanding of conventions used in simple line graphs.
Module Images: CD-ROM / online
Procedure:
Explain: “This image is a graph that comes from the CD-ROM (or from online). The graph plots a series of temperature measurements taken by a balloon as it rises from the ground into the sky.”
Explain: “This is an example of a kind of data graph which is called a line graph. It is called a line graph because individual data points are connected by small, straight line segments.”
Ask: “What is a ‘data point?’” [A data point represents one single observation or measurement.]
Ask: “In this graph, what does the vertical or Y axis stand for?” [The label at the top tells us that it shows altitude in kilometers]
Ask: “In this graph, what does the horizontal, or X axis stand for?” [The label indicates that it represents temperature in degrees Celsius]
<<< Advance the slide to fly-in a circle surrounding the top-most data point>>>
Ask: “This dot represents one of the data points from the balloon. The height of this dot tells us that when this measurement was taken, the balloon was about 17 kilometers above the ground. To find the temperature, we read straight down from the data point, and we can see that it was about -77 degrees.”
<<< Advance the slide to fly-in a circle surrounding another data point>>>
Ask: “Tell me the altitude and temperature for this data point.” [Altitude is about 11 kilometers, temperature is about -56 degrees Celsius.]
Ask: “Tell me the altitude and temperature for this data point.” [Altitude is about 3 – 3.5 kilometers, temperature is about -19 degrees Celsius.]
Explain: “When the data points have been plotted, then connected with lines, it makes it easy to see the overall pattern. When they are all put together, all of those short like segments look like one big, curvy line – and that big line is showing us what happens to the temperature as you go higher and higher into the atmosphere.”
Ask: “What happens to the temperature as you gain altitude?” [it gets colder and colder.]
Explain: “There is one other thing you should start doing whenever you see any kind of diagram or graph – you should always ask yourself WHY the artist drew the picture in the exact way that they did.
Ask: “For example, the light-blue, criss-cross lines are called grid lines. Why do you think the artist put those in the graph?” [Students may say that it makes it easier for the artist to plot the data points in the first place – but the important idea is that those who make graphs make their decisions in order to make it easier for the READER, and not for the artist. In this case, if necessary, guide them to the idea that the grid lines make it easier for the reader to approximate the altitude and temperature – just as you did in the first part of this exercise.]
Ask: “Why do you think that the data points, the boarder, and the grid lines are all blue?” [In this case there is no certain answer, and students may have several different ideas. These may include ‘because the sky is blue, and this is about something rising into the sky’ – or – “blue means cold, and this is about how cold it is as you go up’ – or even – ‘because blue is pleasant to look at.’ The important point right now is to encourage them to consider details of diagrams, and try to figure out why they were drawn that way. This is a sophisticated way to think of visually presented information, and is a valuable habit.]
>>>end of exercise<<<

13. READING Complete the “Think Questions” at the end.
Starting on page 43 read “Weather Balloons and Upper- Air Soundings”
Complete the “Think Questions” at the end.
READING

14. SOUNDING This is the set of data from a weather balloon.
Open to page 81 in the Resource Book, where you will find sounding for 4 different cities.
What 4 cities are represented?
Phoenix, Chicago, Boston, San Fransisco
What information is recorded?
Dew point, air temperature, and altitude

15. EXAMPLE OF PLOTTING DATA
The data for Oakland has been done
Let’s go over it.
EXAMPLE OF PLOTTING DATA

16. ANALYZING THE DATA Open up to page 40 of your lab book.
Each person in your lab group will plot the data for one of the cities.
Graph the altitude vs. air temperature in red
Graph the altitude vs. dew point in green
Altitude (Meters)
ANALYZING THE DATA
Air Temperature and Dew Point

17. COMPARE CITIES SOUNDING
How are the plots alike?
Both air temperature and dew point decrease as the balloon rises.
How are the plots different?
Some dew point and air temperature lines cross; others do not cross or even come close.

18. THINKING ABOUT CONDENSATION
What is dew point”
The temperature at which condensation occurs.
Look at the graph for your city. Did condensation occur anywhere along the balloon’s upward journey? How do you know?
If the air temperature were the same as the dew point, condensation could have occurred.

19. THINKING ABOUT CONDENSATION
What would you expect to see in the sky if condensation occurred?
Clouds
Which cities most likely had clouds on this day? Why do you think so?
Chicago and Boston because the dew point and temperature lines are almost the same.

20. THINKING ABOUT CONDENSATION
At what altitude might you expect to see clouds in Boston on this day?
Between 800 and 1700 meters
Would you have expected to see clouds in Phoenix? Why or Why not?
Probably not. The temperature and dew point lines never crossed.

21. REVIEW OF ATMOSPHERIC MOISTURE
What is water vapor?
The gaseous form of water. It is invisible.
How do the processes of evaporation and condensation affect the amount of water vapor in the air?
When energy is added to a liquid water, it can evaporate, adding water vapor to the air. When water vapor cools it condenses forming liquid water. Clouds and precipitation form.

22. REVIEW OF ATMOSPHERIC MOISTURE
What is relative humidity?
The amount of water vapor in air compared to the amount of water vapor needed to saturate the air at a specific temperature. Recorded as a percentage.
How does temperature affect relative humidity?
If temperature increases, relative humidity decreases and vice versa.

23. REVIEW OF ATMOSPHERIC MOISTURE
What ingredients are needed to make a cloud?
Moisture, energy transfer, and condensation nuclei. Temperature needs to decrease to the dew point so water can condense on cloud nuclei.