Comparing Actual Temperatures to the Standard Atmosphere

For this assignment, you will use the data collected from the weather balloon which was launched during our NWS virtual tour to make graphs of the actual temperature and dew point profiles found in the atmosphere that day. The data and graph paper can be found here:

Week 4 Handouts - NWS Wx Balloon Data 20210923 00z Download Week 4 Handouts - NWS Wx Balloon Data 20210923 00z

Week 11 Handouts - Graph paper (semi-log)

Follow the instructions below in making your graphs. Note that you will be plotting both the temperature and dew point data on the same sheet of graph paper. You do not have to plot every point on the data sheet.

Before you begin, print out an extra copy of the data for you to mark-up and make notations. Here are some suggestions:

• Draw a vertical line between the temperature and dew point columns - don't confuse them.
• Identify the areas where the temperature-dew point spread changes from 5 degrees C or less to over 5 degrees C and vice versa. This will help you in determining the best points to include on your graph.
• Place a mark on your data sheet next to the row containing the values you decide to plot.

Making the Measured Temperature Profile (pressure vs. air temperature)

1. Using a red pencil, plot the temperature values for the pressure levels.

• plot only up to 100 mb
• plot the very first value
• plot values for 925, 850, 700, 500, 400, 300, 250, 200, 150, and 100 mb
• plot at least 10 more values
• do not plot values very close to each other
• for values below -75 C, either omit or plot into the margin

2. With all of the temperature points plotted, use your red pencil to connect them with straight lines for a profile graph of temperature.

• use a straight edge to connect all points
• use caution not to skip any points as you connect them

Making the Measured Dew Point Profile (pressure vs. dew point temperature)

3. Using a blue pencil, plot the dew point temperature values for the pressure levels.

• plot only up to 100 mb
• plot the very first value
• plot values for 925, 850, 700, 500, 400, 300, 250, 200, 150, and 100 mb
• for the remaining points, also plot a dew point value to correspond with each temperature value plotted
• for values below -75 C, either omit or plot into the margin

5. If the dew point is the same as the temperature then circle the red temperature dot in blue.
6. With all of the dew point values plotted, use your blue pencil to connect them with straight lines for a profile graph of dew point temperature once again be careful not to skip over any points

• use a straight edge to connect all points
• use caution not to skip any points as you connect them

Completing the Graph

6. Color the 0 C temperature division on your graph using a yellow highlighter or pencil (vertically top to bottom).
7. Using a green highlighter or pencil, lightly shade in-between the temperature and the dew point profiles where the difference is 5 C or less. This difference between the temperature and the dew point is the temperature-dew point spread (also called the dew point depression). Check your data sheet to be sure this difference is correct before you mark your graph.
8. Add a meaningful title to the top of your graph. Be sure to include:
   • The station name - NWS Detroit Pontiac
   • Date and Time for this observation (Sep 23,2021, 00z)
   • The data you are representing (temperature and dew point)

Scoring for this portion of the Assignment

	Description	Value
1.	Temperature graph	25
2.	Dew point graph	25
3.	0 C line.	5
4.	Shading temp.-dew point spread of 5 C or less	5
5.	Proper graph title	5