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, 20 September 2001, 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 Brownsville, Texas (BRO) at 00Z 19 SEP 2001. The atmosphere over Brownsville has been warm as it is one of the most southerly stations in the US and we are just beginning to exit the summer season.

    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 1009-mb surface pressure is plotted just below the 1000-mb line.] Connect the adjacent points with dashed straight lines.

              Pressure (mb)     Temperature (°C)   Altitude (m)
                  100               -74.5             16640
                  111               -76.7             16036
                  300               -31.1              9720
                  500                -5.7              5890
                  700                12.2              3163
                  850                19.8              1512
                 1009  SFC           31.6
    
  2. The Brownsville (BRO) temperature values at the time of observation indicated the tropopause was located at 111 mb. The tropopause, the boundary separating the troposphere from the stratosphere, is located where the temperature begins to be either steady with altitude (isothermal) or to increase with altitude (an inversion). The Brownsville sounding you plotted shows an inversion layer from 111 mb to 100 mb. According to the Standard Atmosphere temperature profile you drew in Item 1 of this activity, the vertical depth ("thickness") of the troposphere over BRO at 00Z 19 SEP 2001 was [(greater than) (equal to) (less than)] standard conditions.

  3. Compare the Standard Atmosphere and the actual BRO temperature profiles. Throughout the lower and middle portions of the troposphere over BRO 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 Brownsville (BRO) at 0000Z 19 SEP 2001. 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 BRO 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 radiosonde observation. Note that temperatures over Brownsville on this day decrease through the troposphere. You can compare the Image 1 DataStreme Stüve temperature profile for BRO with the profile you drew for the same time using fewer data points.

  5. The altitudes in meters above sea level at which the radiosonde sensed the pressures associated with the Stüve scale lines, appear to the left on the diagram. At the time of the BRO 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 BRO at the time of observation occurred at a [(lower) (higher)] altitude than it does in the Standard Atmosphere. This occurs whenever the actual troposphere is warmer than 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 BRO sounding, the surface wind was from the southeast at 15 knots while at upper levels, they were from varying directions with a maximum speed of 25 knots reported about 150 mb.

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, 24 September 2001:

  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.


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