DataStreme Activity 2B:

THE ATMOSPHERE IN THE VERTICAL

Do Now:

  1. Print this file.
  2. Print the Wednesday Image 1 File.
  3. Print (when available) the Thursday, 21 September 2000, Daily Summary File.

To Do Activity:

  1. Read Chapter 2 in STUDY GUIDE, Part A: Narrative.
  2. Go to STUDY GUIDE, Part B: Applications. Start Activity 2B.
  3. Return here (Wednesday Activity B File) when told to do so.

Go To STUDY GUIDE - Activity 2B Now


WELCOME BACK: Procedure continued from STUDY GUIDE.

  1. Upper air observational data are collected twice a day at nearly 70 US stations. The data from selected stations can be viewed via the DataStreme Homepage in tabular, chart, and map form. The following data are from a rawinsonde observation at San Diego, California (MYF) at 00Z 20 SEP 2000. The atmosphere over San Diego has been very warm along with the entire Southwest for the past weeks as was noted in the Daily Weather Summaries.

    On the same vertical atmospheric chart used in question 1 (Activity 2B, p. 2B-2), plot the reported temperatures at the surface (SFC) and at the pressure levels shown in the table below, . [Note: The pressure scale given on the left side of the graph decreases upward! Consequently, the 991-mb surface pressure is plotted just above the 1000-mb line.] Connect the adjacent points with dashed straight lines.

              Pressure (mb)     Temperature (°C)   Altitude (m)
                  100               -70.5             16620
                  133               -72.3             14929
                  250               -43.7             10973
                  500                -3.5              5890
                  700                12.8              3152
                  850                27.4              1481
                  991  SFC           25.6
    
  2. The San Diego (MYF) temperature values at the time of observation indicated the tropopause was located at 133 mb. The tropopause, the boundary separating the troposphere from the stratosphere, is located where the temperature begins to be steady with altitude (isothermal) or begins to increase with altitude (an inversion). The San Diego sounding shows an inversion layer beginning at 133 mb. According to the Standard Atmosphere temperature profile you drew in Item 1 of this activity, the vertical depth ("thickness") of the troposphere over MYF at 00Z 20 SEP 2000 was [(greater than)
    ( equal to) (less than)] standard conditions. Note that in this actual sounding, the temperature also increases with altitude from the surface to 850 mb. This region from 991 mb to 850 mb is an [(isothermal) (inversion)] layer.

  3. Compare the Standard Atmosphere model and the actual MYF temperature profiles. Throughout the lower and middle troposphere over MYF when the actual observation ("sounding") was made, it was [(warmer) (colder)] than the Standard Atmosphere.

  4. Image 1 is the plotted DataStreme Stüve diagram for San Diego (MYF) at 0000Z 20 SEP 2000. The Stüve diagram is one of a variety of vertical diagrams used in meteorology to display atmospheric soundings acquired by rawinsondes. The temperature and pressure scales are the same as those in the figure on which you drew part of the Standard Atmosphere. (You have already plotted data on a Stüve diagram!) In addition to the temperature and pressure lines that are used in this activity, other sets of lines appear. These will be referred to in later activities. Soundings for temperature and dewpoint for MYF are plotted as "curves" on the Image 1 diagram. The curve to the right with higher values is the temperature profile. It is plotted by computer using all the data points reported from the observation. Note that temperatures generally (but not always!) decrease through the troposphere as shown by the Standard Atmosphere.

    Compare the Image 1 DataStreme Stüve temperature profile for MYF with the profile you drew for the same time using fewer data points. The more detailed curve of Image 1 shows that from about 950 mb up to about 900 mb, the temperature in this layer [(increased) (decreased)] upward. (Your plot also generally implied this feature). As mentioned earlier, the temperature structure in this layer is called a temperature inversion. Another layer with a temperature inversion can be seen from about 660 mb to 640 mb. (As mentioned in item 7, a temperature inversion is also located above the tropopause.)

  5. The altitudes in meters above sea level where the radiosonde sensed the pressures associated with the Stüve scale lines, appear to the left on the diagram. At the time of the MYF sounding, the pressure of 500 mb occurred at an altitude of _______ m. In the Standard Atmosphere 500 mb is found at 5574 m (18,289 ft.) The 500-mb pressure level over MYF at the time of observation occurred at a [(lower) (higher)] altitude than it does in the Standard Atmosphere.

Note: Several items of information from the sounding are listed across the top margin of the Stüve diagram for each station. TROP represents the pressure level of the tropopause. Other items will be defined as they are needed. Wind observations at various levels are plotted to the right of the diagram. In this MYF sounding, the surface wind was from the northwest while at upper levels, they were from the northeast.

DataStreme delivers upper atmospheric data from rawinsonde observations in both Stüve diagrams ("Stüves for selected cities") and tabular form ("Upper Air Data - Text") for selected radiosonde sites in the US via the Homepage. You or your students might wish to plot the upper air data for your nearest site on a blank Stüve diagram ("Blank Stüve - T, p lines") found under Extras on the Homepage. These plots can then be compared with the computer-analyzed version. View Stüve diagrams when weather systems pass your location. Atmospheric structure changes during frontal passages and major storms can be quite dramatic.


Faxing Instructions:

After completing this week's applications, fax the following pages to your LIT mentor by Monday, 25 September 2000:

  1. Chapter 2 Progress Response Form (Part B: Applications, Week 2, also)
  2. 2A and 2B Activity Response Form
  3. STUDY GUIDE, Part B: Applications, page 2B-2

Note: Permission is hereby granted to DataStreme Project participants for the reproduction, without alteration, of materials contained in DataStreme publications and delivered via the DataStreme Homepage for non-commercial use in schools or in other teacher enhancement activities on the condition their source is acknowledged. This permission does not extend to delivery by electronic means.


Return to DataStreme Homepage

URL: datastreme/learn/b_act.html
©Copyright, 2000, American Meteorological Society