Chapter 7: The Atmosphere and Human Activities

Question 1

What are aerosols?

Answer 1

are sprays containing fine particles and/or droplets that becoem suspended in the atmosphere
solid particles could be - particles of dust, salt, fine sand, and volcanic ash

Question 2

What are variable gases?

Answer 2

are gases whose quantity may keep changing as a result of various processes
e.g. Carbon dioxide and Ozone - can keep changing because of evaporation, transpiration, varying rates of formation, pollution, and seosonal changes

Question 3

What are the permanent gases of the atmosphere? (give their percentsge)

Answer 3

Nitrogen - 78.09% - needed for growth of plants
Oxygen - 20.95% - roduced by photosynthesis and used in reporation

Question 4

What are the variable gases in the atmosphere? (give percentages)

Answer 4

Water Vapour - 0.2-4% - source for all types of precipitation/provides most of the greenhouse gases/vital to existence of life
Carbon Doxide - 0.03% - used by plants in photosynthesis/isa greenhosue gas
Ozone - 0.00006% - absorbs ultra violet radiation

Question 5

What are the inert gases in the atmosphere?

Answer 5

Argon - 0.93%
Helium/Neon/Krypton - trace amounts
can create an inert atmosphere that protects materials from reacting with oxygen and other gases

Question 6

What are the non gaseous particles in the atmosphere?

Answer 6

Dust - trace - absorbs and reflects incoming shortwave radiation/water vapour condenses on particles forming droplets or ice crystals which are the basis of cloud formation
Ash/Volcanic ash

Question 7

What are the pollutants in the atmosphere?

Answer 7

Sulfur dioxide/nitrogen dioxide/methane - trace amounts - can lead to smog/acid rain/ozone depletion/enhanced greenhouse effect

Question 8

Describe the basic structure of the atmosphere

Answer 8

1) Troposphere - temperature falls as height rises - upper limit is the tropopause
2) Stratosphere - temperature rises as height rises - upper limit is the stratopause
3) Mesosphere - temperature falls as height rises - upper limit is the mesopause
4) thermosphere - temperature rises as height rises -upper limit thermopause

refer to diagram on page 158

Question 9

Describe the troposphere

Answer 9

• layer surrounding earth’s surface
• temperature decreases with height - averaging 6.4 degree celsius km - because the warming effect of the earth’s surface (through conduction and convection) diminishes as altitude increases
• gravitational pull declines with altitude - so does pressure
• wind speeds increase with height
• upper limit - tropopause - temperatures here remain constant - usually occurs at a height of 8 km at the poles and 17km in the tropics and marks the upper limit to the earth’s weather and climate

Question 10

Describe the Stratosphere

Answer 10

• extends to about 50 km above the earth’s surface
• pressure continues to fall but temp increases steadily with height
• temperature inversion occurs
• acts as shield against incoming meteorites which burn out when entering earth’s gravitational field
• upper limit - stratopause

Question 11

What is temperature inversion

Answer 11

when temperature increases with altitude
is caused in the mesosphere because of the concentration of ozone which absorbs the incoming ultraviolet radiation from the sun

Question 12

Describe the mesosphere

Answer 12

• 50-80 kms in height
• pressure continues to decrease and temp falls rapidly below -80 degree celsius because there is no water vapour/dust/ozone ot absorb incoming short wave radiation
• winds can reach speeds of upto 3000km h
• mesopause - upper limit

Question 13

Describe the thermosphere

Answer 13

• 80 - 1000km
• temperatures rise rapidly to as high as 1500 degree celsius due to the absorption of ultra violet rays by atomic oxygen
• thermopause - upper limit

Question 14

Describe the natural greenhouse effect