Exercises: Atmospheric Stratification and Circulation Cells

List the four main thermal layers of the atmosphere in order from Earth's surface upward. Then name the layer in which most weather occurs.

Name the atmospheric layer that contains the ozone layer. State what kind of radiation ozone absorbs and why this is important for living things.

Describe the Hadley cell. State where air rises, where it sinks, and the approximate latitudes involved in each.

In the stratosphere, oxygen and ozone interact with ultraviolet (UV) light:

1. Explain how these reactions form the ozone layer.

2. Explain why the temperature in the stratosphere increases with altitude, unlike in the troposphere.

A weather balloon records these temperatures:

1. Identify the layer between each pair of consecutive altitudes.

2. Calculate the average lapse rate in the troposphere in $^\circ\text{C}$ per km.

3. Explain what the temperature trend between 20 and 50 km tells you about the heat source for that layer.

The three-cell model of global circulation has Hadley, Ferrel, and polar cells in each hemisphere.

1. Describe the direction of the surface winds at $15^\circ\text{N}$ and at $45^\circ\text{N}$.

2. Explain why many of Earth's major deserts, such as the Sahara and the Sonoran Desert, are found near $30^\circ$ latitude.

3. Explain why storms generally move from west to east across the United States.

The polar jet stream lies near the boundary between the Ferrel cell and the polar cell. Suppose that, at the altitude of the jet stream, the average temperature at $40^\circ\text{N}$ is $-45\,^\circ\text{C}$ in winter and the temperature at $60^\circ\text{N}$ is $-65\,^\circ\text{C}$, while in summer these temperatures are $-48\,^\circ\text{C}$ and $-55\,^\circ\text{C}$.

1. Calculate the north-south temperature difference in each season.

2. Explain how a larger temperature difference affects the strength of the jet stream.

3. Predict how the jet stream and the typical storm track over the United States differ between winter and summer, and justify your answer.

The atmosphere is made of about 78% nitrogen, 21% oxygen, and 0.9% argon by volume. These proportions stay nearly constant up to about 100 km, where the mixing gives way to separation by molecular mass. Meanwhile, the layers defined by temperature (troposphere, stratosphere, mesosphere, thermosphere) change at much lower altitudes.

1. Compare chemical stratification with thermal stratification of the atmosphere.

2. Explain why ozone, a trace gas, is essential in the stratosphere but a pollutant in the troposphere.

3. Explain how chlorofluorocarbons (CFCs) damaged the ozone layer and why the international agreement to phase them out is an example of effective action.