Atmosphere And Weather Flashcards
What is incoming solar radiation
- shortwave UV Insolation is the only energy input; affected by type of cloud & suns angle
What percentage of incoming solar radiation is scatted by the atmosphere
5%
What percentage of incoming solar radiation is reflected into space by the atmosphere
24%
What percentage of incoming solar radiation is absorbed by atmospheric gases
23%
What percentage of incoming solar radiation is absorbed by Earth’s surface and heats it
48%
What is albedo
The proportion of energy reflected back into the atmosphere
What materials have a higher albedo
- lighter ones (snow & ice)
Since darker surfaces absorb more radiation, the energy has the potential to be transferred to lower layers through what process?
Conduction
What happens if conduction is possible in surface absorption?
- the surface will remain cool since heat is transferred to soil/bedrock, since its encouraged when moisture is present
- heat is released back to surface at night
Why does Earth emit long wave radiation back to space
As its a cold body
What is long wave radiation easily absorbed by
- greenhouse gases
- clouds
- both of which return heat to the surface; greenhouse effect
- heat loss greatest on cloudless nights
What is the day time budget equation
= insolation - (reflected insolation + surface absorption + sensible heat transfers + latent heat transfers + long wave radiation)
What is the night time budget equation
= stored energy - (latent heat transfers + sensible heat transfers + long wave radiation)
How do the clouds have an effect during daytime
- clouds have a net cooling effect due to their albedo value causing insolation to be reflected to space
How do cirrus clouds effect energy
- allows insolation to pass through
- rejects longwave radiation
How to cumulonimbus clouds effect temperature
- they neither heat or cool sufficiently
How do low, thick stratus clouds effect energy
- reflect 80% of insolation, keeping Earth’s surface cool
What 2 processes are included within sensible heat transfer
- convection
- conduction
What is the convection process
- thin air layers are heated above the surface so molecules vibrate more resulting in the gas being less dense making it rise.
- the air cools getting denser and falls to replace rising air
What is conduction
- heat transfer between the ground and the air when they are in contact
Is convection a good conductor
- no, its poor
What is a latent heat transfer
- occurs when water evaporates to water vapour, or ice melts into water vapour
- heat required for the state change is absorbed from the air leaving less energy to heat the surface
- latent heat of condensation increases the speed and extent of convection
What is evaporation
The process whereby a liquid is transferred into a gas when heat is applied.
What is dew
- when water saturated air comes into contact with an object with a temperature cooler than the airs dew point
- water vapour condenses into liquid form
- latent heat is released during condensation adding heat to ground
How do surface temperatures change
- during the day surface is heated by radiation, conduction, convection
- surface air moves slow due to friction, is heated, & rises as a result of convection
- at night ground is cooled by lack of radiation, heat from soil and rocks rises to heat the surface
What is excess in the latitudinal radiation pattern
- positive radiation budget in the tropics
- occurs as insolation is so concentrated
What is a deficit in the latitudinal radiation pattern
- negative radiation budget at higher latitudes
- insolation has a larger amount of atmosphere to pass through; more chance of reflection
- rays are less concentrated
What is a balance in the latitudinal radiation pattern
- neither regions are getting warmer/colder
- horizontal transfer from the tropics to the higher latitudes
Describe the temperature patterns in a latitudinal radiation pattern
- little seasonal variation at the equator
- great variation in mid/high latitudes
- a lag time exists between overhead sun and maximum insolation since atmosphere is heated from below now above
- coldest period is after winter solstice since ground continues to lose heat despite resumed insolation
- greater lag time over ocean due to high specific heat capacity compared to land
What are the atmospheric transfers
- pressure variations
- surface pressure
- surface wind belts
- ocean conveyer belt
What are pressure variations
- where air moves from high to low pressure
- low/declining pressure systems bring poor weather
Why is surface pressure low in equatorial regions
- as warm air rises and leaves the surface
Why are higher pressures seen in polar regions
- as cool air descends onto the surface
Why are surface wind belts uneven
- due to seasonal variation in insolation
Types of precipitation
- clouds
- rain
- hail
- snow
- dew
- fog; steam, advection
What is the ocean conveyer belt
- where cold salty water sinks from polar regions and moves towards equator where warm water gives its heat away to the surface winds
- more evaporation in North Atlantic leaving saltier water behind; denser so sinks & cools
- water is transported to pacific; dilutes less dense & rises
What is the dry adiabatic lapse rate (DALR)
- the rate at which a parcel of dry air cools
What is the saturated adiabatic lapse rate (SALR)
- the rate at which a saturated parcel of air cools as it rises through the atmosphere
What are the layers of the atmosphere
- troposphere
- stratosphere
- mesosphere
- thermosphere
What layers of the atmosphere decrease in temperature with height/altitude
- troposphere
- mesosphere
What layers of the atmosphere increase in temperature with height/altitude
- stratosphere
- thermosphere
What does the atmospheric heat budget of the earth depend on
- the balance between incoming solar radiation (insolation) and outgoing radiation from the planet
What are the 6 components in the daytime energy budget
- incoming shortwave solar radiation
- reflected solar radiation
- surface absorption
- sensible heat transfer
- long-wave radiation
- latent heat (evaporation/condensation)
What are the 4 components of a night time energy budget
- long-wave earth radiation
- latent heat transfer (condensation)
- absorbed energy returned to earth
- sensible heat transfer
What is the environmental lapse rate (ELR)
- the decrease in temperature usually expected with an increase in the height through the troposphere
What happens to atmospheric (air) pressure as you move up through the atmposhere
- decreases
What is sensible heat transfer
- the transfer of parcels of air to or from the point at which the energy budget is being assessed
What is the sub-surface supply
- refers to the heat transferred to the soil and bedrock during the day which is released back to the surface at night
What is condensation
- when water droplets form after the air is cooled to its due point
How can condensation occur
- radiation from ground during clear night
- warm wind blowing over cold ground
What is humidity
- refers to how moist the air is because of the water vapour it contains
What is absolute humidity
- the actual amount of water vapour in a given volume of air
What is relative humidity
- measures how near the air is to saturation
- indicated how much water vapour the air is holding compared to the maximum amount it can hold at that temperature and air pressure
What’s are the 3 types of rain
- frontal
- relief/orographic
- convectional
What is frontal rainfall’s
- where warm air meets cold air
- warm air is forced over the cold air
- in doing so, it cools and condenses = precipiation
What is convectional rainfall
- when the sun heats up the ground, water on the ground evaporates and rises into air as water vapour
- when it gets colder the water vapour condenses and falls as rain
What is relief/orographic rainfall
- when air is blown against a line of hills it is forced to rise
- as it rises it cools; water vapour condenses forming water droplets
What is dew
- direct deposition of water droplets onto a surface
- occurs in clear, calm anticyclonic conditions
- temperature reaches dew point further cooling causes condensation
What is hail
- alternate concentric rings of clear and opaque ice
How is hail formed
- by raindrops being carried in vertical air currents by cumulonimbus clouds
- raindrops freeze as they are carried high up in cumulonimbus cloud
- when really big the updraughts in the cloud can’t hold them anymore so fall to earth, not having time to melt before hitting the ground
What is snow
- frozen precipitation
How is snow formed
- when the temperature is below freezing and water vapour is converted into a solid
- very cold air contains limited moisture; heaviest snowfalls tend to occur when warm mist air is forced over high mountains or when warm moist air comes into contact with cold air at a front
What is an air mass
- a large volume of air that has the same characteristics; temperature & moisture
How is absorbed energy returned to earth
- greenhouse gasses absorb reradiated longwave radiation and atmosphere warms
