Unit 4 Flashcards
The atmosphere
– Thin, shell-like envelope of life sustaining air that surrounds the Earth – Consists of gases, liquids, and solids – Reactions occur throughout the atmosphere
atmospheric elements
- Temperature
- Humidity
- Cloudiness
- Precipitation
- Pressure
- Wind speed/direction
atmospheric pressure
the weight of the air above
– At sea level, the average
atmospheric pressure (MSLP) is close to 1000 millibars
-DECREASES EXPONENTIALLY WITH HEIGHT
Relationship between mass and height
inverse; atmospheric mass decreases with height
it is caused by_____
origin of the atmosphere
• 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
physical atmospheric processes
– Change in the appearance of a substance in which it can change
back to its original state
• Ex: Phase changes of water
chemical atmospheric processes
– Change of a substance into a new one that has a different chemical identity
•Ex: Lightning
biological atmospheric processes
– With life involved, change a
substance into a new one with a different chemical identity
• Ex: Photosynthesis
homosphere
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
constant gases
– Found in same percentages all over world – Little yearly or seasonal variation – Constant gases include: • Nitrogen • Oxygen • Argon
nitrogen
– 78 percent
– Nearly inert
– Residence time = 13 million years
oxygen
– 21 percent – Crucial for life – 3 forms of Oxygen • O • O2 • O3* – Residence time = 5,000 years
argon
– 0.9 percent
– Inert gas
– Residence time = infinite
trace gases (variable gases)
– Constitute only a tiny proportion of the air – Present in varying quantities – Trace gases include: • Carbon dioxide • Water Vapor • Ozone (O3) • Methane
carbon dioxide (trace gases)
– 0.04 percent or 390 ppm – Most important for climate change • Absorbs and emits longwave (terrestrial) radiation – Residence time = around 40 years
water vapor (trace gases)
– 1 to 4 percent
• Deserts and cold regions vs. oceans and warm areas
– Crucial for clouds and rainfall
– Residence time = less than two weeks
ozone (o3)
– Rarer type of oxygen molecule – 2 to 10 ppm – Good absorber/transmitter of longwave (terrestrial) radiation – Absorbs UV (solar) radiation
methane (CH4)
– 1.8 ppm – Better absorber of longwave (terrestrial) radiation than carbon dioxide – Residence time = 10 years
Particulates
– Any suspended or falling liquid or solid • Clouds • Sea salts • Fine soils • Smoke • Soot • Pollen • Ash • Nongaseous components
heterosphere
• Extends beyond the homosphere in the upper region where the chemical composition changes • Gases start to settle according to molecular weigh
arrangement of atmosphere
– Altitude has a major influence on
temperature
• Divided into 4 spheres
• Separated by 3 pauses
troposphere
– 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?
tropopause
• Boundary between troposphere and
stratosphere
• Height varies with latitude
stratosphere
– Stratosphere • 15 to 50 km (9 to 32 mi) • Thinner, clear air than troposphere • Jets fly here • Ozone layer – Temperature inversion
stratopause
• Boundary between stratosphere and
mesosphere
mesosphere
- 50 to 95 km (31 to 60 mi)
- Temperature decreases with height
- Coldest temperatures on Earth
mesopause
• Boundary between mesosphere and
thermosphere
thermosphere
• 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
ideal gas law
A basic relation between pressure, density, and temperature of air
