Introducing the atmosphere Flashcards
describe composition of the atmosphere
nitrogen, oxygen, water vapour, argon and trace gases incl CO2
what is the world’s oldest and primary measuring site for CO2 gas concentrations?
Mauna Loa Observatory, Hawaii
what was the concentration of CO2 in 1960
315 ppm
what is the current concentration of CO2
nearly 420 ppm
why do CO2 concentrations fluctuate throughout the year?
northern hemisphere growing season reduces CO2 between may and september. Northern hemisphere dominates due to greater landmass and plant biomass
why are sulphates more common in winter of the NH
more fossil fuels being burned
function of ozone
protection from UV radiation
what percentage of ozone is in which layer?
90% in stratosphere
what is the concentration of ozone
8ppm
how much of the troposphere is used by humans?
5km
which states of water hold the most and least energy?
ice- lowest energy, liquid water- intermediate energy, water vapour- high energy
what happens when water moves from a low-high energy state
it absorbs heat energy
what does it mean when something is saturated
no. of molecules that evaporate= no. of molecules that condense
what is saturation rate?
max concentration of H2O molecules that can reside in the vapour phase at any specified temperature
why does sweating keep you cool?
water (sweat) absorbs the heat and evaporates
what is vapour pressure
measure of the amount of water in a parcel of air/ how much of measured pressure caused by water vapour
what causes the carrying capacity of air to rise
rising temperature
where is ocean salinity high and why
high evaporation regions, as more water is evaporated into the atmosphere, leaving lots of salt behind
what happens when saturation vapour pressure is reached
condensation occurs to turn vapour to liquid and remove the water
what happens when saturated air is heated
the capacity increases and it becomes undersaturated
what is relative humidity
ratio of vapour pressure in sample of air, to saturation vapour pressure at the same temp
(how much water in the air out of how much water could be in the air)
why does breathing out on a cold day condense quickly
cold air cannot hold much water vapour
what is dewpoint
when the relative humidity of the air reaches 100% and condensation begins
what are adiabatic processes
compressional warming and expansional cooling without the addition or subtraction of heat from external sources
what is the lapse rate
rate of temperature change with altitude
explain the adiabatic (dry) lapse rate
rate of unsaturated warm air cooling as it rises… 10C per km
explain the environmental (wet) lapse rate
rate of saturated warm air rising and cooling. Cools more slowly than adiabatic lapse rate due to the release of latent heat… 6.5 C per km
what happens in relation to the adiabatic lapse rates when cloud formation occurs
parcel reaches saturation point and the dry adiabatic lapse rate changes to the moist rate
name the four main air lifting forces
density lifting (convection) frontal lifting (2 masses of diff density meet) convergence lifting (2 air masses meet and are forced up) orographic lifting (forced over sloping terrain, produces rain shadow)
what provides the surface for condensation at dewpoint
condensation nuclei, which are small particles of dust etc (aerosols), means less energy is needed for condensation
how do raindrops form from the condensed vapour in clouds?
when the density of droplets increases before coalescing and falling
