Motion in the Atmosphere Flashcards
What is the passage of an isolated parcel of air that is warmed by short wave radiation from the Sun?
An isolated parcel of air (lets say) close to the surface is heated and rises, because on warming its density becomes lower than that of the surrounding cooler air.
Pressure falls with height in the atmosphere, as the parcel rises it also expands so that the internal pressure of the parcel and the external pressure are equal.
Expanding parcel of air chills because its molecules lose a little of their internal energy, as they bounce of retreating parcel walls.
What are adiabatic temperature changes?
There is no interchange of heat between the parcels and its surroundings.
This also means a constant entropy change.
What happens when a rising air parcel cools?
It may cause the air to become saturated with water vapour, condensation to take place and clouds and precipitation to form.
What happens when water vapour condenses o form water droplets in the rising air parcel?
What is the saturated adiabatic lapse rate?
It releases latent heat which warms the air slights and therefore causes the rate of temperature decrease with height to fall below the dry adiabatic lapse rate.
The new lapse rate in the presence of condensation.
What is the troposphere?
As some air masses rise, others descend, so the lower atmosphere is continually turning over.
The troposphere is this layer of large scale mixing which contains most of atmospheric water vapour.
What is the tropopause?
The upper boundary of the troposphere, which has an altitude of about 5-6 km over polar regions and 15-16 km over equatorial regions.
What is the stratosphere?
It extends from the top of the tropopause to about 50km height (the stratopause).
Why in the stratosphere does temperature vary very little with height or increases with height with warmer air overly?
The maximum temperatures are associated with the absorption of the Sun’s short wave radiation by ozone which is found at this altitude.
Why does temperature increase with altitude?
Because of the absorption of extreme UV radiation by oxygen but really these ‘temperatures’ are theoretical because there is so little air.
Why is it that over timescales of a year or longer, the complete Earth-atmosphere system is almost in thermal equilibrium and so consequently the total global absorption of solar radiation by the Earth’s surface and the atmosphere must be balanced by the total global emission to space of infrared radiation?
Most solar rdiation is absorbed during the day in tropical regions.
Infrared radiation is lost continually day and night to space from whole of Earth’s surface and atmosphere.
Heat energy is therefore transferred from tropics, to middle and high latitudes, where it is in deficit, by NORTH-SOUTH CIRCULATIONS in the atmosphere and oceans.
What are rossby waves?
High altitude, fast moving westerly winds which often flow an irregular path which changes throughout the seasons.
What causes rossby waves?
May be caused by presence of substantial mountain barriers e.g. Rockies
Meridional air flow has a
a large north-south component
Cold air tends to flow downhill by katabatic drainage causing
frost hollows
Subtropical westerly jet stream
– Poleward boundary of the tropical Hadley cell
– Just below tropopause
– In winter it divides around the Tibetan Plateau
