6.1 Introduction to the Atmosphere

Question 1

Atmosphere

Answer 1

The layer of gases surrounding Earth, held in place by gravity, which is essential for supporting life, regulating climate, and protecting against space radiation. It extends from the Earth’s surface up to the exosphere.

Question 2

Five layers of the atmosphere (top to bottom)

Answer 2

Exosphere
Thermosphere
Mesosphere
Stratosphere
Troposphere

Question 3

Composition of the atmosphere

Answer 3

Nitrogen 78%
Oxygen 21%
Carbon Dioxide 0.04%
Other gases: less than 1%

Question 4

Troposphere

Answer 4

The lowest layer of the Earth’s atmosphere, extending from the surface up to about 8-15 kilometers.

It contains most of the atmosphere’s mass and is where weather events occur.

Question 5

Stratosphere

Answer 5

The layer of the Earth’s atmosphere above the troposphere, extending from about 15 kilometers to 50 kilometers.

It contains the ozone layer

Question 6

Tropopause

Answer 6

The boundary layer between the troposphere and the stratosphere, where the temperature lapse rate changes from decreasing to increasing with altitude.

Question 7

VOCs (Volatile Organic Chemicals)

Answer 7

Organic chemicals that easily vaporize at room temperature and contribute to air pollution. Common sources include paints, solvents, and fuel vapors.

Question 8

PM (Particulate Matter)

Answer 8

Tiny solid or liquid particles suspended in the air (including dust and pollen), categorized by size (e.g., PM10, PM2.5). It can affect respiratory health and visibility.

Measured as mass/volume of air (not ppm - which is used for gases)

Question 9

SO2 (sulfur dioxide)

Answer 9

A colorless gas with a pungent odor, produced by burning fossil fuels and industrial processes. It can cause respiratory problems and contribute to acid rain.

Question 10

NOx (nitrogen oxides)

Answer 10

A group of gases including nitric oxide (NO) and nitrogen dioxide (NO₂) that contribute to air pollution, smog, and acid rain.

Question 11

Difference between NO (nitric oxide) and NO2 (nitrogen dioxide)

Answer 11

Nitric oxide (NO) is primarily formed during high-temperature combustion processes, while nitrogen dioxide (NO₂) is typically formed through the oxidation of NO in the atmosphere (a secondary pollutant).

Question 12

N2O (Nitrous oxide)

Answer 12

A colorless gas. Used as a performance enhancer in engines. It is a potent greenhouse gas and contributes to ozone layer depletion.

Not a NOx

Question 13

CO (Carbon monoxide)

Answer 13

A colorless, odorless gas produced by incomplete combustion of carbon-containing fuels. It can interfere with oxygen transport in the blood and is a common indoor air pollutant.

Question 14

Secondary compound (pollutant)

Answer 14

A chemical compound that forms in the atmosphere through reactions involving primary pollutants. For example, ozone (O₃) is a secondary pollutant formed from reactions involving NOx and VOCs.

Question 15

Air Pollution

Answer 15

The presence of harmful or excessive quantities of substances in the air, including gases and particulate matter, which can affect human health, ecosystems, and the climate.

Question 16

Ppm (parts per million)

Answer 16

How gases are measured in the atmosphere.

If carbon monoxide (CO), is present at a concentration of 1 ppm in the air, it means there is 1 molecule of carbon monoxide for every 1 million molecules of air.