Basics Of Climate Change Flashcards
What is climate?
The statistical properties of meteorological conditions over a given period
What is the given period for studying climate?
30 years
What is the atmosphere?
A relatively thin layer of gases that is held around the Earth by gravity
Where is the troposphere?
Between the surface and 8-15km
Where is the troposphere deepest and shallowest
Deepest at the tropics, shallowest at poles
Does temp increase or decrease with altitude in the troposphere?
Temp decreases with altitude
What is the lapse rate?
Lapse rate is the gradient of temperature in the atmosphere
Where is the tropopause?
Top of the troposphere
Where is the stratosphere?
From top of tropopause to 50km
Does temp increase or decrease with altitude in the stratosphere?
Temp increases with altitude
Where is the ozone layer located?
In the stratosphere
Where is the mesosphere located?
From the stratosphere to 80-100km
Does temp increase or decrease with altitude in the mesosphere?
Temp decreases
Where is the thermosphere?
From the mesosphere up to 600km
What is the exosphere?
The uppermost layer of the atmosphere
What is the relationship between sunlight received and latitude?
Sunlight received (Wm^-2) is proportional to cos(latitude)
Where is the most and least sunlight received?
Max at equator, minima at poles
Is incoming sunlight long or shortwave?
Shortwave
Is outgoing terrestrial radiation long or shortwave?
Longwave
What is a cell e.g. Hadley cell, polar cell
Direct circulations caused by heating and ascent in atmosphere/surface
Where is the Hadley cell? What direction are the solar winds?
At the equator between 0 and 30 degrees, direction away from equator
Where is the polar cell, what direction are the solar winds?
At the poles, between 60 and 90 degrees, direction away from equator
Where is the Ferrel cell, what direction are the solar winds?
Between Hadley and polar cell between 30 and 60 degrees, direction towards equator
What is the relationship between sunlight absorbed and outgoing terrestrial radiation?
Sunlight absorbed=outgoing terrestrial radiation
What does Coriolis force do?
Leads to the deflection of flows to the right in northern hemisphere and to the left in Southern Hemisphere
What is the net function of atmosphere and ocean?
To distribute the heat from the equator pole wards
What are the characteristics of cirrus clouds?
Cold, thin, high up, made of ice
Why do high clouds trap more energy than low clouds?
Not much solar radiation reflected back to space, lots of terrestrial radiation absorbed
Do high clouds warm or cool environment
Warm
Why do low clouds trap less energy that high clouds
They reflect more solar radiation to space, and smaller LW radiative forcing
Do low clouds warm or cool the environment?
Cool
What is cloud radiative forcing?
The difference between radiation emitted to space for average atmospheric conditions, and then also without clouds for same region and time period
Describe why SW CRF is negative
More clouds in the sky create a higher albedo, and more SW is reflected back to space.
Therefore SWCRF fullsky > SWCRF clear, so SWCRF is -ve
What is the equation for SW CRF
SW CRF = SWclearCRF - SWfullskyCRF
Describe why LW CRF is positive
More clouds in the sky mean more LW radiation trapped at the surface, so less LW radiation is emitted to space.
LWclear CRF > LWfullsky CRF,
Therefore LW CRF =+ve
What is the equation for LW CRF?
LW CRF= LWclear CRF - LWfullskyCRF
What is the equation for net CRF
Net CRF = SW CRF - LW CRF
What is the atmospheric pressure equation?
mat g /A
90% of atmospheric mass is less than what altitude?
Less than 10km
What is atmospheric pressure measured in?
Pascals
What is the ideal gas law?
P = ρR T
ρ= density
R= specific gas constant
p=pressure
What is the first law of thermodynamics?
du = dq + dw
u = internal energy
q = heat energy
w = work
How is the first law of thermodynamics written for atmospheric sciences?
dq = cpdT -alpha dp
cp = specific heat at constant pressure
Alpha =1/density
p =pressure
What is radiative forcing?
The change in the net energy balance at the tropopause from pre-industrial to present day caused by a perturbation to atmospheric conditions
What are the units for radiative forcing?
Wm-2
What things may radiative forcing impact?
Incoming solar radiation
reflected solar radiation
outgoing longwave radiation
What effect does positive radiative forcing have?
More energy going in than going out, so earths overall temp will increase
Why effect does negative radiative forcing have?
More energy going out than in so earths overall temp will decrease
What does GCM stand for?
General circulation model
What is a GCM (not what the letters mean)
A type of climate model built up from discretised Navier Stokes equations
What is the relationship between global mean temp change and radiative forcing?
They’re proportional
dTsurf =λ RF
λ= climate sensitivity parameter (K/W m-2 )
What do GCMs do?
Allow for assessment of the evolution of global mean temperatures (and more)
What is lambda? (GCM context)
-Climate sensitivity parameter
-normally determined from equilibrium GCM simulations
-approx independent of forcing mechanism
-differs among climate models :(
What is the directional relationship between magnetic and electric fields?
They’re perpendicular
What is the relationship between wavenumber an wavelength?
Wavelength (lambda) = 1/wave number (nu)
Which has the higher wavelength, red or blue light?
Red
What temp and wavelengths is black body radiation emitted from the sun?
6000K
UV, visible, near IR
What temp and wavelengths is black body radiation emitted from the Earth
300 K
Near and far IR
What is the equation for isotropic emission?
M(T) =pi B(T)
What are some assumptions about the ‘Ball-Bearing Earth?’
1) no atmosphere
2) So invariant between equator and poles
3) alpha =reflected solar radiation/So =planetary albedo
What are some assumptions about the Stefan-Boltzmann law?
1) no atmosphere
2) black body (emissivity =1)
3) surface area of Earth = 4 pi R2
What is the relationship between solar radiation and terrestrial radiation at steady state?
Solar radiation absorbed =terrestrial radiation emitted
So(1-α) πR2 = 4π R2σ T4
What does the atmosphere consist of?
78% N2
21% O2
1% other gases
What is Rayleigh scattering?
Scattering of radiation caused by interaction of radiation with molecules
What are the most significant absorbing components in the atmosphere?
O2 and O3
CO2
H2O
How does the atmospheric absorption vary between solar and terrestrial wavelengths?
0.3-3.0 microns: mostly non-absorbing
3.0-100 microns: mostly absorbing
How can the ‘ball-bearing’ earth model be improved?
Add an atmosphere layer characterised by emissivity =absorptivity
What is an atmospheric aerosol?
Consists of suspension of fine solid/liquid particles suspended in the troposphere or stratosphere
Name some effects of aerosols on clouds
Increase cloud albedo
Increase cloud height
Increase cloud lifespan
Drizzle suppression
Name the orders of the atmosphere
Troposphere -> stratosphere -> mesosphere -> thermosphere -> exosphere
