0.9 Rice air curriculum - lesson 2 (teacher): physical properties

Objective

Students will begin to take the following measurements outside—the amount of ozone in the air, surface temperature and air temperature, types of clouds in the air, humidity, and wind direction. These measurements will continue for five class periods. At this point in time, students do not have enough knowledge to analyze the results they get. Creating hypotheses, drawing conclusions, and communicating their findings about the trends in data will occur later in the course. However, you can involve the students in experimental design by helping to select exactly where to take the measurements.

Students will spend a lot of this lesson getting familiar to the tools they will be using to take measurements at the beginning and end of the class. Teachers should refrain from explaining too much about how the instruments work, unless necessary, so as to allow students the freedom to explore on their own how to make the measurements Students will be introduced to the layers of the atmosphere and will learn about two of the tangible properties of the atmosphere that they will be measuring with their GLOBE instruments: temperature and winds.

Background information

The Earth’s atmosphere is divided into five layers. The first layer, closest to earth’s surface, is the troposphere . This is where all of our weather occurs—clouds, wind, lightning, hurricanes, rain, snow, and tornadoes. Because air density is greatest near the surface and diminishes with height, the troposphere contains about 80% of the atmosphere’s mass. All of the air we breathe is in the troposphere, so it is here that air pollution is of greatest concern. Temperature is typically warmest near the ground and cools with height in the troposphere, which helps drive the weather and the mixing of pollutants.

The next layer is the stratosphere . This is where ultraviolet radiation from the sun reacts with oxygen to form ozone gas and the ozone layer. The oxygen and the ozone layer protect us from the cancer-causing ultraviolet radiation. This absorption of radiation causes temperatures to increase with height in the stratosphere, in contrast to cooling with height in the troposphere. This temperature pattern causes the stratosphere to be very stable; in other words, air rises and sinks very slowly in this layer.

The next layer is the mesosphere , which stops meteors and other fragments of things that come from space. The next layer is the thermosphere, where space shuttles orbit the earth. Finally, the last layer is the exosphere, which is the outermost portion of our atmosphere and is the layer in which satellites orbit the Earth. Outside of this layer lies space.

Layers of the atmosphere

The two most obvious ways that we experience the atmosphere are through its temperature and its winds. Temperature is a physical property that measures how “hot” or “cold” something is. Microscopically, it is a measure of the average kinetic energy or speed of the molecules that make up the system. Temperature can be measured in Kelvin, Celsius, and Fahrenheit.