Unit 4

Question 1

The atmosphere

Answer 1

– Thin, shell-like envelope of life 
sustaining air that surrounds the 
Earth
– Consists of gases, liquids, and solids
– Reactions occur throughout the 
atmosphere

Question 2

atmospheric elements

Answer 2

• Temperature
• Humidity
• Cloudiness
• Precipitation
• Pressure
• Wind speed/direction

Question 3

atmospheric pressure

Answer 3

the weight of the air above
– At sea level, the average
atmospheric pressure (MSLP) is close to 1000 millibars
-DECREASES EXPONENTIALLY WITH HEIGHT

Question 4

Relationship between mass and height

Answer 4

inverse; atmospheric mass decreases with height

it is caused by_____

Question 5

origin of the atmosphere

Answer 5

• Formed through a combination of volcanic outgassing and material
from outer reaches of solar system
• Early on mostly consisted of water vapor and carbon dioxide
• Planet eventually cooled allowing water vapor to condense and fall as
rain
– Falling rain drops carried carbon dioxide from the atmosphere to the ocean
– Could combine with other materials forming carbon bearing rocks and organisms
• Photosynthesis increased oxygen amounts

Question 6

physical atmospheric processes

Answer 6

– Change in the appearance of a substance in which it can change
back to its original state
• Ex: Phase changes of water

Question 7

chemical atmospheric processes

Answer 7

– Change of a substance into a new one that has a different chemical identity
•Ex: Lightning

Question 8

biological atmospheric processes

Answer 8

– With life involved, change a
substance into a new one with a different chemical identity
• Ex: Photosynthesis

Question 9

homosphere

Answer 9

Lower region of the 
atmosphere
• Uniform chemical composition
• Almost all of the atmospheric 
mass is found in this region
• Homosphere contains:
– Constant gases
– Trace gases
– Particulates

Question 10

constant gases

Answer 10

– Found in same percentages all over world
– Little yearly or seasonal variation
– Constant gases include:
• Nitrogen
• Oxygen
• Argon

Question 11

nitrogen

Answer 11

– 78 percent
– Nearly inert
– Residence time = 13 million years

Question 12

oxygen

Answer 12

– 21 percent
– Crucial for life
– 3 forms of Oxygen
• O
• O2
• O3*
– Residence time = 5,000 years

Question 13

argon

Answer 13

– 0.9 percent
– Inert gas
– Residence time = infinite

Question 14

trace gases (variable gases)

Answer 14

– Constitute only a tiny proportion of the air 
– Present in varying quantities
– Trace gases include:  
• Carbon dioxide
• Water Vapor
• Ozone (O3)
• Methane

Question 15

carbon dioxide (trace gases)

Answer 15

– 0.04 percent or 390 ppm
– Most important for climate change
• Absorbs and emits longwave 
(terrestrial) radiation
– Residence time = around 40 years

Question 16

water vapor (trace gases)

Answer 16

– 1 to 4 percent
• Deserts and cold regions vs. oceans and warm areas
– Crucial for clouds and rainfall
– Residence time = less than two weeks

Question 17

ozone (o3)

Answer 17

– Rarer type of oxygen molecule
– 2 to 10 ppm
– Good absorber/transmitter of 
longwave (terrestrial) radiation
– Absorbs UV (solar) radiation

Question 18

methane (CH4)

Answer 18

– 1.8 ppm
– Better absorber of longwave 
(terrestrial) radiation than carbon 
dioxide
– Residence time = 10 years

Question 19

Particulates

Answer 19

– Any suspended or falling liquid or 
solid
• Clouds
• Sea salts
• Fine soils
• Smoke
• Soot
• Pollen
• Ash
• Nongaseous components

Question 20

heterosphere

Answer 20

• Extends beyond the 
homosphere in the upper 
region where the chemical 
composition changes 
• Gases start to settle according 
to molecular weigh

Question 21

arrangement of atmosphere

Answer 21

– Altitude has a major influence on
temperature
• Divided into 4 spheres
• Separated by 3 pauses

Question 22

troposphere

Answer 22

– Troposphere
• Lowest 15 km (9 mi) 
• All life and weather occurs here
• Temperature decreases with height
– Average lapse rate = 6.5 C/km 
(3.5F/1000ft)
– Lapse rate?

Question 23

tropopause

Answer 23

• Boundary between troposphere and
stratosphere
• Height varies with latitude

Question 24

stratosphere

Answer 24

– Stratosphere
• 15 to 50 km (9 to 32 mi)
• Thinner, clear air than troposphere 
• Jets fly here
• Ozone layer
– Temperature inversion

Question 25

stratopause

Answer 25

• Boundary between stratosphere and

mesosphere

Question 26

mesosphere

Answer 26

• 50 to 95 km (31 to 60 mi)
• Temperature decreases with height
• Coldest temperatures on Earth

Question 27

mesopause

Answer 27

• Boundary between mesosphere and

thermosphere

Question 28

thermosphere

Answer 28

• 95 to 1000 km (60 to 620 mi)
• Temperature increases with height 
due to the absorption of very 
shortwave, high energy solar radiation 
by atoms of oxygen and nitrogen.
• Auroras

Question 29

ideal gas law

Answer 29

A basic relation between pressure, density, and temperature of air