unit 2 LO1 causes of GCC Flashcards
(41 cards)
definition climate vs weather
Climate = long term behaviour (>30y) of the atmosphere in an area
Weather = state of atmosphere at a given time and place
gas comp in atmos
nitrogen (78)
oxygen (21)
argon (0.9)
+ trace (CO2, helium, ozone)
why co2 affects gcc more than nitrogen and o2 even tho it is way more minute
it is an efficient absorber of energy (emitted by earth) = influences heating of atmosphere. GH gas
(N and O little influence)
how is the atmophere arranged
a series of imperfectly shaped cocentric layers or spheres - grade into each other
BOUND TO EARTH BY GRAVITY
vertical structure of atmosphere 4
Thermosphere - vacuum (incr absorbed e due to energised sw rad)
Mesosphere - temp decr (decr density)
Stratosphere - stable, thin (no dust and water v) incr in temp with height (solar rad)
Troposphere - most weather processes (temp fall as atmos thins)
what are the inbetweens of the atmosphereic structure (4) called
(part before) -pause
eg
mesopause , tropopause
which layer does weather occur in
trophosphere (temp decr as height incr)
- rate of temp decr = environmental lapse rate
what is environmental lapse rate
rate of temp decr as height incr in the troposphere
whatis the tropopause
an isothermal layer (constant temp)
- upper limit to troposphere + earth climate and weather
system of atmosphere
a balance betw –> incoming and outgoing rad
annual balance = earth’s energy budget
how is atmospheric energy balance maintained 2
energy from the sun + heat transfers
how does nenergy from the sun conttribute to energy balance
- atmos is open e system
- e from sun - shortwave
- lost from earth - longwave
how does heat transfers contribute to the BALANCE of energy in the atmosphere
- earth absorbes solar energy in tropical regions (loss of e from poles)
= redistribution of e from lower latitudes to higher latitudes (wind circulation, ocean currents)
– horizontal heat transfer
how are wind and ocean currents responsible for balance of e in atmos
heat transfers
wind 80%
ocean currents 20%
define atmospheric energy budget
the annual balance of incoming and outgoing radiation
energy balance in the energy budget is
the amt of e ABSORBED must be = amt RELEASED
atmospheric budget numberssss
only 46% gets thru to earth surface
- 31% reflected back into space
- 19% absorbed by atmos gases
- 8% scattering
- 17% clouds and water droplets (clouds can reflect up to 80%)
- 6% reflection from earth surface (planetary albedo)
3 ways balance is acheived
- radiation (no need for medium - can travel thru space)
- convection - movement of gas or liquid (most heat from lowest area in atmos is transported this way)
- conduction - transfer by contact (air near surface)
define greenhouse effect
process by which certain gases allow sw rad from sun to pass thru, but TRAP incr proportion of lw rad
– leads to warming of atmosphere
- NATURALLY OCCURING
define counter radiation
reflection of lw rad back to earth bc greenhouse effect
main gases in global warming
CO2
methane
CFCs
encahnced gh effect
acceleration of eh effect due to human activities
- harmful to climate
- more lw rad trapped
= greater amt of warming
gh effect: co2
co2 levels risen from 315ppm in 1950 to >400ppm in 2012
- due to human activities – fossil fuel burning, deforestation
gh effect: methane
- 2nd largest contributor
- incr 1% per annim
- cattle – 100 mil tonnes / year
