Frist Half Flashcards
(37 cards)
what is the difference between climate and weather?
Weather = state of the atmosphere at a given time
climate = avg weather over a long period of time (typically 30yrs)
- it is a statistical measure and does not typically vary much
- climate systems also includes the oceans, cryosphere, vegetation and lithosphere as well as the atmosphere
two methods of weather observation
global surface weather stations
upper air radiosonde (balloon) stations in north america
surface weather stations “stevenson screen”
white box about 1 m off the ground
measures humidity, temp, pressure and wind
white to minimize overheating
vents to allow air flow
anemometer is 1m above ground to measure wind
weather balloons
measure the lowest 30km of the atmosphere twice a day around the world
measures temp, moisture, wind and these are used to create weather maps at diff altitudes
when the balloon reaches 30km the balloon bursts and the measuring package is dropped
4 different observations that show climate change is actually happening
- global annual mean surface air temp
- global mean sea level
- arctic summer sea ice extent
- atmospheric carbon dioxide concentration and ocean acidification
evidence 1: global mean surface temp
in the last 50yrs the global surface temp has increased by 1 degree celcius
warming hiatus from 2002 to2012
last 5 years have the warmest since 1880
evidence 2: global mean sea level
increasing at about 3.4mm/yr = 34 cm/ 100yrs
it is going to increase no matter what but it can be kept to a minimum
better indicator of climate change because it better indegrates on a global scale the effects of increased radiative forcing
two reasons why the sea levels are rising
- Melting land ice (not sea ice in the north pole) in greenland, antarctica and glaciers
- thermal expansion - as ocean waters heat up the water molecules move more and therefore take up more space, increasing volume without increasing mass
evidence 3: arctic sea ice extent
loosing 0.83 million square km per decade
lg amount of inter-annual variability
in the linear decline observed in the las 40yrs continues, the arctic will be ice free in 50 years
evidence 4: increasing atmospheric CO2 and its effect on ocean acidification
increasing CO2 in environment warms climate and acidifies the oceans
what happens to atmospheric pressure and air density with height?
both decrease exponentially
the decreasing air pressure with height creates an upward pressure that balances the downward force of gravity - this is called hydrostatic pressure
the atmospheric layers and their boundaries
troposphere: closest to the earth, active weather is here, clouds and precipitation, weather impacted by earths surface
equatorial tropopause= boundary
stratosphere: also the ozone layer, clear, very dry and stable
- the ozone layer protects us from harmful UV radiation by absorbing it ( this is why temp actually increases with height in this layer)
stratopause = boundary
mesosphere: temp decreases with height bc of ozone heating
mesopause
thermosphere - extends to space where the thermopause in theory exists
chemical composition of air
constant gasses: Nigtrogen Oxygen argon neon helium hydrogen
variable gasses: water vapour carbon dioxide nitrous oxide carbon monoxide chlorofluorocarbons
ozone
this gas is a minor player in climate change
most of it is found in the stratosphere where is absorbs harmful UV radiation from the sun - doesn’t reach earths surface
ozone in the troposphere is considered to be air pollution and is formed photochemically from nitrous oxides ( as a result of fossil fuel burning)
- ground level ozone is harmful to humans and plants
residence time
average lifetime of a molecule in the atmosphere
total mass in reservoir/ mass outflow rate
issue with residence time for carbon dioxide
according to the formual it is only 5 years
however the CO2 were adding is nowpart of the total climate system and goes intoplants and oceans fora few years and then comes back into atm so were not permanently removing it
reality is it takes hundreds of years to actually remove it
only way to get rid of it completely is to deposit it at the bottom of the ocean on the sea floor
hydrological cycle
this is the water cycle
evaporation/condensation transfer large amount of heat from the surface to air
then you get land percipitation
also have soem evaporation and transpiration
percoaltion = water flows into groud then ground water flows back into ocean
important facts about the ocean
71% of earths surface = ocean
ocean = 97% of earths water
avg depth is 3.7km deep
- deepest point is 11km
important for climate change because of their ability to store and transport huge amounts of energy and to delay temperature response because of its huge heat capacity
what is the temperature at the bottom fo the ocean and why?
bottom of ocean is very cold
the thermocline is the layer where the ocean temp decreases rapidly with depth
the deep ocean is cold bc the water source is the polar sea surface
- the densest water will be cold and salty and therefore sinks to the bottom of the ocean
properties of electromagnetic spectrum
amplitude
wavelength
frequency
waves are described based on specifying wavelengths or frequency
thermal radiation
radiation emitted by substances based on its temperature
the hotter the material the more radiation is emitted
- material gets hotter, radiaiotn being emitted shifts to shorter wavelengths
all matter emits electromagnetic radiation in accordance to its temperature
most solid surfaces and liquids are able to absorb and emit radiation at all wavelengths efficiently
black bodies
the material is able to absorb and emit radiation at 100% efficiency
gasses do not act as black bodies because they absorb and emit at very specific wavelengths
infrared radiation (IR)
invisible radiation with wavelengths that are longer than the visible red wavelengths
2 types for climate studies: solar infrared, terrestrial
solar infrared
near-infrared or shortwave infrared radiation
emitted by the sun
makes up approx. half of solar radiation
