2. Atmosphere and Weather Flashcards
What is an energy budget
The amount of energy entering a system
The amount of energy being transferred in a system
The amount of energy leaving the system
What are the 6 components of the daytime energy budget
Incoming solar radiation Reflected solar radiation Surface absorption Sensible heat transfer Long-wave radiation Latent heat of evaporation
Incoming solar radiation
aka insolation
affected by latitude, season and cloud cover
Energy coming from the sun
Only 23-40% of insolation reaches the surface of the Earth
shortwave radiation from the sun
Reflected solar radiation
aka Albedo
Light materiels are more reflective than dark materiels
Water only has an albedo of 4%
Surface absorption
energy that reaches the earth’s surface and heats it
Rock is a poor conductor of heat
if the surface can conduct heat to lower layers then it will remain cool
Sensible heat transfer
Movement of air into and out of a specific area
rise of warm air and replacement by cooler air
Long-wave radiation
The radiation of energy from the earth into the atmosphere.
during the day there is a net loss of energy from the surface
Latent heat transfer (evaporation)
The energy used to evaporate water, which means that less energy will be available for raising local energy and temperature
4 factors of the night time energy budget
Longwave earth radiation
latent heat transfer (condensation)
Sub-surface supply
Sensible heat transfer
Long wave radiation at night
Loss of energy during cloudless nights
Reduced loss of energy during cloudy nights
Longwave radiation in hot areas
often cloudless nights
maximised energy loss
large diurnal temperature differences
Latent heat transfer (condensation)
At night, water vapour close to the surface condenses to form water as the air has been cooled by the cold surface. when water condenses, latent heat is released
Sub-surface supply
Heat transferred to the soil and bedrock can be released back to the surface at night.
offsets night time cooling a bit
Sensible heat transfer at night
cold air moving into an area reduces temperatures where as warm air may supply energy and raise temperatures
Warm air
rises
Absolute humidity
the amount of water in the atmosphere
Relative humidity
Water vapour in the air as a percentage of the maximum amount that can be held
increases as temperature rises
saturated air
relative humidity of 100%
Mist
visibility is reduced to between 1000m-5000m
relative humidity is 93%
Fog
visibility is reduced to >1000m
requirements for mist and fog to form
condensation nuclei e.g dust
condensation of moist air cools below its dew point
occur near ground level
how does condensation take place
cooling of air
more water added to atmosphere
calm, high pressure conditions required to prevent the air from mixing with drier air
e.g: water evaporates from warm surface and condenses into the cold air above to form fog
Advection fog
when warm air flows over a cold surface. the warm air reaches 100% relative humidity
Radiation fog
When the ground loses heat at night by longwave radiation. occurs during high pressure conditions
Dew
condensation on a surface as the temperature has dropped to increase the relative humidity
Temperature inversions
reversal of the normal temperature behaviour of the troposphere. cold air on the bottom
greenhouse gases
trapping of longwave radiation
tropics have a
positive budget
the poles have a
negative budget
How is the budget balanced between the poles and tropics
horizontal transfer of energy from equator to the poles via wind and ocean currents
When are the solstices
Jan, jun.
shortest days
When are the equinoxes
march, sept
longest days
high pressure
good weather
low pressure
poor weather
ITCZ
intertropical convergence zone
where winds between the tropics converge. an area of low pressure
Latitudinal variations of the ITCZ
a result of the movement of the overhead sun. In June the ITCZ is further north, in Dec it is further south
Doldrums
Light winds at the ITCZ
2 factors that affect the temperature on a global scale
angle of the overhead sun, thickness of the upper atmosphere
temperature at the equator
high quality insolation, insolation received for a long time, less atmosphere to pass through
temperature at the poles
sun is low in the sky, poor quality of insolation, thick atmosphere, high albedo
Specific heat capacity
the amount of heat energy required to raise an amount of water by 1 C
why does water heat slower
it is clear which allows the suns rays to be distributed across a wider area
tides and currents also distribute heat
How does the sea influence temperature
Water releases heat much more slowly than the land. in winter, sea air is much warmer than land air so onshore winds bring heat to coastal lands. however in summer coastal areas remain coller than inland sites
what are areas with coastal influence called
maritime or oceanic
how are surface ocean currents created
the prevailing winds blowin steadily over the sea
what are the patterns of surface ocean currents
clockwise in the northern and anticlockwise in the south
gulf stream
transports heat northwards then eastwards towards the british isles
oceanic convection movement
in polar regions, cold salty water sinks into the depths and makes its way to the equator
what factors affect air movement
pressure and wind, pressure gradient
air motion
air motion is caused by the unequal heating of the earths surface
pressure gradient
air blows from high pressure to low pressure . the poles have a high pressure, equator has a low pressure
coriolis effect
deflection of objects caused by the easterly rotation of the earth
air flowing from high pressure to low pressure is deflected to the right in the north and to the left in the south
geostrophic balance
balance between pressure gradient force and coriolis force
friction decreases…
wind speed, coriolis force
