Atmosphere Flashcards
Composition of air varies with altitude:
Nitrogen (78%) and oxygen (21%) make up 99 percent of the volume of the air
The atmosphere is divided vertically into four layers on the basis of temperature:
troposphere, stratosphere, mesosphere, thermosphere
Troposphere?
layer in which we live, where nearly all weather occurs.
Temperature decreases with an increase in altitude
Weather vs. Climate:
Weather is the state of the atmosphere at any given time (e.g. temp, wind, precipitation)
Climate – long-term average weather conditions in a specific place or region.
weather vs climate again
Weather is constantly changing (hour by hour, day by day)
Climate based on observations over many decades.
The weather today may or may not be indicative of the climate.
Basic Elements of Weather & Climate:
The most important elements are
(1) air temperature
(2) Humidity (moisture content)
(3) type and amount of cloudiness
(4) type and amount of precipitation
(5) air pressure
(6) the speed and direction of the wind
Adiabatic Lapse Rate:
temp. of dry air decreases by about 10 ̊ C per km
Temp. of moist air decreases by about 5 ̊ C per km
Stratosphere:
The boundary between the stratosphere and troposphere is called the tropopause
Temperatures rise through the atmosphere
This is due to ozone absorbing UV rays
Although the ozone is thinner at top of stratosphere, it absorbs enough energy to keep the warmer temperature.
Mesosphere
Stratopause marks the end of the stratosphere (-pause just means the barrier between two spheres of the atmosphere)
Temp begins to decrease with height at mesopause
The coldest temps in the atmosphere occur in the mesosphere
Thermosphere
The mesopause marks the end of the mesosphere and the beginning of the thermosphere
No well-defined upper limit
Although the temp is hot, it would not feel hot because there are very few air molecules
Ionosphere
Includes portions of the thermosphere and upper mesosphere
Here molecules of nitrogen and oxygen are ionized (become charged)
Electrons are then free to travel as electric current
The aurora borealis and aurora australis are found here
The Natural Greenhouse Effect
With no greenhouse effect, average temperature on earth would be around -18°C
That is more than 30 degrees colder than current average temp
The Natural Greenhouse Effect
With no greenhouse effect, average temperature on earth would be around -18°C
That is more than 30 degrees colder than current average temp
Main Greenhouse Gases
(Contribution to Greenhouse Effect)
Water Vapour (36-72)%
Carbon Dioxide (9-26%)
Methane (4-9%)
Ozone (3-7 %)
Nitrous Oxides (<1%)
Chluorofluorocarbons (CFCs) (<1%)
Water Vapour (H2O)
Naturally occurring in the atmosphere
Can only be altered at a local level by humans
Short residence time in atmosphere
