Our atmosphere is warmed by shortwave radiation received from the Sun. Some of the energy is reflected back to space depending on cloud cover and the surface characteristics of Earth. Some of the energy is absorbed by the surface, then re-emitted back to space as longwave radiation. As this occurs, clouds and atmospheric gases can reflect, absorb and re-emit this energy — the so-called greenhouse effect. This naturally-occurring balance of energy makes Earth habitable. Refer to Earth's Energy Budget for a visual of this phenomena.
Most human activity and weather occurs in the troposphere. The air temperature generally decreases with height away from the surface. In the stratosphere, the ozone layer absorbs the energy from the Sun, protecting us from harmful ultraviolet radiation. The temperature in the stratosphere actually increases with height because of this. Where this thermal reversal occurs is the boundary between the troposphere and stratosphere called the tropopause. The tropopause is not the same height everywhere. It is higher in the tropics than at the poles. (Refer to the Vertical Structure of the Atmosphere)
To form clouds, evaporated moisture needs to condense into droplets. Before that can occur, the air must become saturated (humidity must reach 100 percent). Usually, this occurs when moist air rises and cools. The temperature when saturation occurs is called the dew point temperature. When air temperature equals dew point temperature, clouds will be found.
In this exercise, students will examine air temperature, dew point, wind speed and air pressure data collected by radiosonde. They will access real time data sets and create graphs using Microsoft Excel.
The prerequisite knowledge, materials, and vocabulary are laid out in this resource.
I like to begin this lesson with some background information and tell my students that we are going look at actual data collected in the last 12-24 hours from Earth's atmosphere obtained from radiosondes. Since this is first time most have heard to this technology a short presentation on the history of atmospheric observations is helpful and informative.
The following links will provide you with lots of information from which to choose:
In addition, I found this powerpoint that does a nice job tying it all together.
You will need one computer with internet access and Microsoft Office for every two or three students, or printed copies of atmospheric data. If your students have not used Microsoft Excel before, you will want to allow more time to guide them through using this program. While not a difficult activity, there are several steps to follow to get data from the web site to a graph. I always budget two full classes for this lesson.
Be sure to have students plot the altitude on the y-axis and pressure or temperature on the x-axis. This will create a graph that shows the change in pressure/temperature vertically with increases in altitude. Have them print their graphs and attach them to their labs for grading.
You can find the data at University of Wyoming Atmospheric Soundings. Make sure to model for the students how to access this site and search for data sets that are complete up to at least 30,000m. That way students are able to graph data up into the stratosphere and compare this data with prior knowledge of Earth's atmospheric layers. (Practice 4 Analyzing and Interpreting Data)
To get started, select a station from the map. For instance I selected Upton, NY (OKX) (station map).
This brings to me to the most recent data set for this station Upton data header.
You must then scroll to the bottom of the data set to see if it extends up to 30,000m and be sure that you have a complete data set.
If it stops before 30,000m or is incomplete up to to 30,000m, you must select a different station before continuing on.
1. After analyzing the data with a graph, students can make a pictorial scale wall chart. Ask students to label altitudes and atmospheric layers. Ask students to find graphic representations of what they would find in each layer such as animals on the ground, jet planes at their altitude, balloons, satellites and the International Space Station in their proper distance.
2. To give students a better perspective on the thinness of our atmosphere, ask students to find a local city or town near their location that is the same distance away as the distance from the surface to the top of the atmosphere.
3. Find other radiosonde data on the Internet (University of Wyoming Atmospheric Sounding) for other locations and dates. Make Excel graphs using similar procedure, and determine cloud layers and other features.
4. Hypothesize the patterns you would expect to see regarding the relationship between land and ocean temperatures. Compare radiosonde graphs of a location inland and a location near the coast or on an island. Discuss your findings.
In the video below two of my students explain how this activity helped them make sense of data.
Once completed you can lead the class in a discussion on the results of their graphs. Here are some some suggested questions to guide the talk.
1. What explanation can you offer as to the shape of the data on the temperature vs altitude graph?
2. Do the temperature and dew point temperature ever meet on this day? Do you think any clouds were visible?
3. Can you find the tropopause in the data? At what altitude or pressure does it occur?