Chapter 3 Flashcards
The atmosphere can be divided by…
- Composition
- Function
- Temperature
List the categories for COMPOSITION:
HOMOSPHERE (bottom/ under 80k)
- Same composition of gases (nitrogen, oxygen, etc)
HETEROSPHERE (top part/ above 80k)
- Different elevations men different gasses. Heaviest at the bottom, lightest at top.
List the categories for FUNCTION:
OZONOSPHERE
IONOSPHERE
List the categories for TEMPERATURE:
THERMOSPHERE
STRATOSPHERE
MESOSPHERE
TROPOSPHERE
Photochemical Smog
Result of the interaction of sunlight and the combustion products in automobile exhaust
PARTICULATE MATTER
diverse mixture of fine particles, both solid and liquid, that pollute the air and affect human health.
examples: haze, smoke, dust, sulfate aerosol
Black carbon / Soot
an aerosol having devastation health effects in developing countries
- absorbs heat in the atmosphere and changes the reflectivity of surfaces such as snow and ice
Haze
concentration of microscopic particles and air pollution that diminishes clarity
Air
simple mixture of gases that is naturally odorless, colorless, tasteless, formless, blended so thoroughly that it behaves as if it were a single gas.
Extent of the Atmosphere
480km
Carbon Dioxide
Natural by-product of life, a variable gas that is increasing rapidly
- absorbs radiation, warming the earth
- too little causes global cooling
Air pressure
Air molecules create air pressure (through their motion, size and number,) exerting forces on all surfaces they come in contact with
- measured in force per unit area
Why are CFC’s bad for the ozone layer?
Chlorofluorocarbons react with UV light to release chlorine which then destroys ozone molecules.
Insolation
- Exposure to the sun’s rays
- Intercepted solar radiation
HETEROSPHERE
80km-480km altitude
Gases are not evenly mixed. They occur in distinct layers sorted by gravity according to their atomic weight.
HOMOSPHERE
Earth’s Surface - 80km altitude
With exception of the ozone layer and variations in pollution, and water vapour in the lower atmosphere, it is composed of a near uniform mixture of gases.
Gases in the Homosphere (5)
Nitrogen
Oxygen
Argon
Carbon Dioxide
Trace Gases
THERMOSPHERE
80-480 km in altitude
Temperatures increase with altitude
1200 °C + temperatures, but not “hot”
Height depends on solar activity (less solar activity = lower)
MESOSPHERE
50-80 km altitude
Temperatures decrease with altitude.
Cosmic + meteoric dust provide nuclei for ice crystals to form. (notillucent clouds)
Extremely low pressures
STRATOSPHERE
18 - 50 km altitude
Contains the OZONE LAYER
Temperatures increase with altitude
TROPOSPHERE
Sea Level - 18 km altitude
- Thickness controlled by surface temperatures (18 km at equator, 8km at poles)
- temperatures decrease with altitude (normal lapse rate which is 6.4 °C)
- Mixing of air of troposphere and stratosphere is prevented because troposphere is cooler, denser than stratosphere which is warmer, less dense
Tropopause
Occurs wherever -57°c in the troposphere is measured.
Mesopause
averaging at –90°C, the coldest part of the atmosphere.
Stratopause temperature
0°C
Thermopause
Approximately 480 km in altitude that serves conceptually as the top of the atmosphere
“-pause”
Where one layer of the atmosphere ends and another begins. Generally defined by temperature change.
Normal Lapse Rate
The average rate of temperature decrease with increasing altitude in the lower atmosphere
aprox 6.5 C°/km
Environmental Lapse Rate
The actual rate of temperature decrease with increasing altitude in the lower atmosphere at any particular time and place.
varies between 5-12C°/km
Temperature Inversion
Occurs when the normal temperature, which usually decreases with altitude (normal lapse rate), reverses trend and begins to increase at some point.
Cause of Temperature Inversion
Cold dense air has warmer less dense air overlying it.
This stops mixing and the air in the lower portion becomes trapped (in an inversion layer).
Pollutants are trapped beneath the inversion.
Ozonosphere
Ozone layer
Responsible for the absorption of harmful UV rays
- three oxygen molecules
- UVB and UVA are absorbed and reradiated as infared rays
Ozone
Ozone is a highly reactive oxygen molecule made up of three oxygen atoms (O3) instead of the usual two atoms (O2) that make up oxygen gas.
Function of Ozone
Ozone absorbs…
100% of UVC
90% UVB
50% of UVA
3 types of UV
UVA
UVB
UVC
Dobson Unit (DU)
Measure of the concentration of ozone in the atmosphere,
Global average dobson Unit
300,000DU
Dobson Unit Value where we consider it a ‘hole in the ozone’
Under 220,000 DU
What harms the ozone layer?
Compounds containing Chlorine and Bromine (eg. Chlorofluorocarbons)
Science of Ozone Depletion chemistry
Cl + O3—-uv—-> ClO+ O2
and
ClO+ O3—-uv—-> Cl+ 2O2
The process of ozone depletion through the chemical reaction with Chlorine is an example of…
a positive feedback loop
The ozone depletion reaction is assisted by the
Sun
Ozone depletion explained
Occurs when CFC’s and sunlight react, breaking down Ozone, causing a hole in the ozone layer.
Special conditions of Ozone depletion reaction
Extremely Low temperatures (Conditions for Polar Stratospheric Clouds)
UV (sunlight)
Solid Surface
Polar Stratospheric Clouds
Clouds made up of small particles of ice (ice crystals). They provide the solid surface required for the two ozone depleting chemical reactions to occur.
Antarctic Vortex
High velocity of wind that circulates around Antarctica.
It contains the highest concentration of CFCS (they get sucks in). Locus of the worst destruction of the ozone.
Worst ozone damage occurs when?
September, when there is the perfect conditions for a combination of lots of sun and low temperatures.
“Bad Ozone”
Ground level ozone is a highly unstable gas.
It damages plants, and irritates human eyes, nose and throats
Exosphere
An extremely rarefied outer atmospheric halo beyond the thermopause at an altitude of 480 km
