Science RWLO Template Title Placeholder

Atmospheric Profiles & Interpreting

Thermodynamic Diagrams

Project Overview

The American Meteorological Society DataStreme Atmosphere website is a science education website which is part of a course designed for K-12 teachers. The website includes real-time weather data (weather maps, satellite images, radar imagery, weather balloon data) that can be easily accessed.

The students will be provided basic foundational knowledge and examples prior to this lesson to help them with their interpretation of this real-time data taken from actual weather balloon information.

After the introduction to some basic theoretical knowledge, this RWLO allows the students the excitement of analyzing real-time weather data -- the exact same data that professional meteorologists are using. This should be much more interesting than using only textbook-type examples. This lesson would occur around midway through a typical semester after fundamental concepts of the basic weather elements have already been studied. By this time, students should have enough knowledge and skill to confidently interpret real-time data presented in a Stuve Diagram.

Student Learning Objectives

For this RWLO, the student will be able to:

·  Differentiate between “weather and “climate”.

·  Draw the Earth’s general atmospheric temperature profile, and identify the atmospheric layers based on temperature.

·  Convert between different units of temperature.

·  Plot data points on a thermodynamic diagram and interpret results.

·  Interpret “sounding” data from a real-time Stuve thermodynamic diagram.

Procedure

Time: Approximately 60 minutes

Materials: Access to the Internet

American Meteorological Society DataStreme Atmosphere Project,

http://www.ametsoc.org/amsedu/dstreme/

For real-time weather sounding data:

http://www.ametsoc.org/amsedu/dstreme/ à “Upper Air” à “Stuves for Selected Cities” à Select a City

For basic background information on Stuve Thermodynamic Diagrams:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “User’s Guide” à “Weather Products” à “Upper Air Information” à “Stuves For Selected Cities”

For basic background information on weather map symbols:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “Weather Map Symbols”

The following tables & graphs (provided in the lesson activities):

- Air Pressure – Air Temperature Table

- General Atmospheric Profile graph

- Blank Atmospheric Thermodynamic (Stuve) diagrams

Prerequisites:

Basic prerequisite skills and knowledge:

- Ability to define and give examples of “weather” and “climate”.

- Weather describes the state of the atmosphere at a particular place and time.

- Climate provides a general description of the atmosphere over a region and/or over a

period of time. This involves the incorporation of statistical weather data and includes

extreme and record conditions in addition to average conditions.

- Ability to draw the Earth’s general atmospheric temperature profile, and identify the atmospheric layers based on temperature. (See Figure 1 of lesson).

- Ability to convert between the different units of temperature (Fahrenheit, Celsius, Kelvin).

- Ability to plot data points on a graph, and to interpret various graph parameters.

- Ability to describe wind data from conventional “wind barb” drawings.

Wind symbol convention can be found in:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “Weather Map Symbols”

Implementation: This RWLO can be used in a meteorology or general science classroom to let students access and interpret real-time weather data originating from launched weather balloons.

General Steps:

1.  Students will first perform basic exercises dealing with the general temperature profile of the Earth’s atmosphere, including the conversion of temperature units, plotting points on a simple thermodynamic graph, and interpreting basic results.

2.  Students will then be introduced to a more complex thermodynamic diagram (similar to the type used by professional meteorologists), and will evaluate and interpret the plotted data found on a real-time diagram.

Content Material

Student Directions:

See activities outlined in lesson:

“Atmospheric Profiles and Interpreting Thermodynamic Diagrams”.

1. Get familiar with Figure 1 – the general temperature profile of the Earth’s atmosphere -- and note the shape of the temperature profile and the different atmospheric layers formed by the temperature changes.

2. Complete Table 1 by converting temperature values from ºC to ºK and ºF. Then plot pressure-temperature points from Table 1 onto Figure 2.

(Conversion formulas can be found in textbooks or in various Internet resources).

3. Answer questions (#3 - #5) dealing with the plotted data in Figure 2.

4. Read and study the descriptions and explanations about Stuve Diagrams and the interpretation of basic data shown on these diagrams.

5. From the given directions (steps #6 and #7), access a real-time Stuve Diagram from the American Meteorological Society DataStreme Atmosphere website and make a copy or printout of the Stuve Diagram. Then answer the questions (#8 and #9) about the data found in the chosen Stuve Diagram. These answers will be based on practical extensions of the previous idealized Figure 2 work.

Referenced URLs:

American Meteorological Society DataStreme Atmosphere Project,

http://www.ametsoc.org/amsedu/dstreme/

For real-time weather sounding data:

http://www.ametsoc.org/amsedu/dstreme/ à “Upper Air” à “Stuves for Selected Cities” à Select a City

For basic background information on Stuve Thermodynamic Diagrams:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “User’s Guide” à “Weather Products” à “Upper Air Information” à “Stuves For Selected Cities”

For basic background information on weather map symbols:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “Weather Map Symbols”

Lesson:

Atmospheric Profiles & Interpreting Thermodynamic Diagrams

Figure 1 displays the average temperature profile of the Earth’s atmosphere from the surface all the way to an elevation of over 70 miles (about 110 kilometers). Based on this temperature profile, the atmosphere is divided into four layers (in order from the surface upward):

-  Troposphere

-  Stratosphere

-  Mesosphere

-  Thermosphere

Almost all of the Earth’s weather is contained within the bottom atmospheric layer – the troposphere.

While Figure 1 displays the average temperature profile of the Earth’s atmosphere, Figure 4 displays specific temperature (plus dew point and wind) conditions over a particular station at a particular time. This figure typically displays data from the surface to the lowest regions of the stratosphere. The data to create these graphs comes from “radiosondes” connected to weather balloons.

Figure 1

General temperature profile of the Earth’s atmosphere

Table 1 below shows the relationship of the “average” air temperature (in units of degrees Celsius) as a function of air pressure (in units of millibars).

Table 1

1. Complete the rest of the table by converting temperature values from ºC to ºK, and from ºC to ºF.

The graph shown by Figure 2 is a type of thermodynamic diagram.

2. Plot the average air temperature as a function of air pressure in Figure 2, and connect your data points.

Your resulting plot is referred to as the standard atmosphere profile

3. Which axis on the Figure 2 graph is linear and which is non-linear? Explain.

(A reminder that the x-axis is the horizontal axis, and the y-axis is the vertical axis).

4. Based on your plotted graph in Figure 2, at what millibar level is the tropopause located at?

Explain how you came to your conclusion.

(A reminder that the tropopause is the boundary between the troposphere and the stratosphere).

5. Does your plotted graph in Figure 2 represent “weather” or “climate”? Explain your reasoning.

Figure 3 is a blank atmospheric thermodynamic diagram (called a Stuve Diagram) which depicts weather data taken by instruments (called radiosondes) connected to weather balloons as the balloons ascend up the atmosphere.

The x-axis shows temperature in (ºC), while the y axis shows air pressure (in millibars) and elevation (in meters) – note its similarity to Figure 2.

Figure 4 is a Stuve Diagram complete with data taken at Buffalo, New York (station abbreviation “BUF”) at 1200Z 14 December 2004.

The two plotted curves in these diagrams (referred to as “soundings”) describe important characteristics of the atmosphere during the time of the balloon launch. The plotted curve on the right is air temperature, while the plotted curve on the left is dew point temperature. In addition, wind velocities at various pressure and elevation levels are displayed at the right edge of the diagram.

We can expect to see clouds and/or precipitation in regions of the atmosphere that have high relative humidity values close to 100%. This usually happens when the "dew point depression" is within 3ºC. In other words, clouds and/or precipitation can be expected in regions where the difference between the air temperature & the dew point is 3ºC or less.

For example:

The Buffalo sounding indicates high probability of clouds and/or precipitation from about 180-meter elevation to 1414-meter elevation (or from about 990-mb air pressure to 850-mb air pressure).

Figure 3
Figure 4

Buffalo, NY Sounding from:

AMS DataStreme Atmosphere Project,

http://dstreme.comet.ucar.edu/stuve.html

From the example in Figure 4:

At the surface:

- air temperature is about -9°C,

- dew point temperature is about -10°C,

- winds are blowing at 10 knots from the NW.

The tropopause appears to be located at about 300 mb.

The air temperature at the tropopause is about -54°C.

The strongest winds are blowing from the WSW at 60 knots (around 140 mb).

See basic information on weather map symbols including wind velocities at:

http://www.ametsoc.org/amsedu/dstreme/ à “Extras” à “Weather Map Symbols”

6. Go to the American Meteorological Society DataStreme Atmosphere website at:

http://www.ametsoc.org/amsedu/dstreme/ à Upper Air à Stuves for Selected Cities

7. Choose a city’s Stuve Diagram to view, then copy or print that diagram.

8. Based on your chosen city’s Stuve Diagram, list the following:

a. The city and its “3-letter identifier”.

b. The air temperature and dew point at the surface.

c. The wind speed and direction at the surface.

d. The speed and direction of the strongest winds,

and the level in millibars.

e. The millibar level of the tropopause.

Explain how you got your answer.

f. The air temperature at the tropopause.

g. The millibar level(s) having a good possibility of clouds and/or precipitation.

Explain how you got your answer.

9. Is this plotted Stuve thermodynamic diagram an example of “weather” or “climate”? Explain your answer.

Teacher Keys/ Basic Example

-  Completed temperature values in Kelvin and Fahrenheit are shown in red in the Table on the next page. (Student answers may be off by 1 or 2 degrees depending on how numbers were rounded off).

(6 pts)

-  The plotted graph from the Table 1 data is shown in the Figure 2 (Key).

(4 pts)

Table 1 (Key)

3. Which axis on the Figure 2 graph is linear and which is non-linear? Explain.

(2 pts)

In Figure 2, the x axis (air temperature in Celsius) is linear while the y axis (air pressure in millibars) is non-linear. The incremental spacing of air temperature values is constant (similar to the numbers on a ruler), while the incremental spacing of air pressure values is not constant (the 100-mb spacing at the bottom of the graph is smaller than the 100-mb spacing at the top of the graph).

4. Based on your plotted graph in Figure 2, at what millibar level is the tropopause located at? Explain how you came to your conclusion.

(3 pts)

The plotted graph in Figure 2, show that the tropopause is located at 226 mb. That is the millibar level at which the air temperature stops decreasing with increased elevation. (Note the boundary between the troposphere and stratosphere as shown in Figure 1).

5. Does your plotted graph in Figure 2 represent “weather” or “climate”? Explain your reasoning.

(2 pts)

The plotted graph in Figure 2 represents “climate” – the air temperatures represent “average” values.

8. Based on your chosen city’s Stuve Diagram, list the following:

(See Stuve Diagram Example which follows)

a. The city and its “3-letter identifier”. (2 pts)

Caribou, Maine – “CAR”

b. The air temperature and dew point at the surface. (2 pts)

surface air temperature = -3ºC

surface dew point temperature = -4ºC

c. The wind speed and direction at the surface. (2 pts)

5 knots blowing “from” the NNE

d. The speed and direction of the strongest winds,

and the level in millibars. (3 pts)

50 knots blowing “from” the SW (at 200 mb & 280 mb)

e. The millibar level of the tropopause. Explain how you got your answer.

(3 pts)

The tropopause is at 350 mb. Again this the millibar level at which

the air temperature appears to stop decreasing with increased

elevation.

f. The air temperature at the tropopause. (2 pts)

The air temperature at the tropopause is about -46ºC

g. The millibar level(s) having a good possibility of clouds and/or precipitation. Explain how you got your answer.

(4 pts)

A good possibility of clouds and/or precipitation can be found at

about 550 mb down to the surface. Here the ‘dew point depression’

(difference between the air temperature and dew point) is 3ºC or

less.

9. Is this plotted Stuve thermodynamic diagram an example of “weather” or “climate”? Explain your answer. (3 pts)

The plotted graphs in Figure 4, and in any of the real-time Stuve diagrams, represent “weather”. The data is for a specific location and specific time.

Practical Stuve Diagram

(Example Key)

Assessment

Students will be assessed on: