Definitions and Atmospheric Structure Flashcards
What is temperature measured in?
Kelvin (SI) Degrees Celsius (non SI)
How do you convert celsius to kelvin?
Kelvin = Celsius + 273.15
What is pressure measured in?
Pascal (Pa) (SI)
What are wind speeds measured in?
- metres per second (m s-1) (SI units)
- knots (kt)
what is humidity measured in?
it is quoted as a % (on SI unit)
What is relative humidity?
water vapour content of the air as a percentage of the maximum possible, saturation or equilibrium vapour content at that temperature
what graph compares vapour pressure and temperature?
Clauius-clapeyron curve
what is dew point?
The temperature to which a parcel of air with constant water vapour content must be cooled, at constant pressure, in order to become saturated
What is dew point depression?
The difference between the temperature of a parcel of air, and its dew point temperature.
Does dew point change with the temperature of air?
No
What is the dew point temperature?
15°C
what is the dew point depression temperature
7°C.
What is mixing ratio?
Ratio of the mass of water vapour to mass of dry air.
What is specific humidity?
The ratio of the mass of water vapour to the mass of moist air
What is absolute humidity or vapour density?
The mass of water vapour per unit volume of moist air.
what is Vapour pressure?
at a given temperature, vapour pressure is proportional to vapour density.
How is time expressed
time is usually quoted in 24 hour form and in UTC (coordinated universal time). This is almost the same as GMT
How deep is the troposphere at the poles and equator?
8km deep at the poles and 16km deep at the equator
How does temperature change in the troposphere?
temperature generally decreases with altitude
Which layer does weather mostly occur in?
The troposphere.
What is the purpose of the tropopause?
prevents exchange of air between the troposphere and stratosphere.
What is the boundary layer?
A sublayer of the troposhere which is in contact with the surface of the earth
What is the boundary layer dominated by?
turbulence and surface exchange processes: heat, moisture and momentum
what doe the boundary layer exhibit?
large diurnal changes in many properties eg depth and temperature
how deep is the boundary layer?
can vary from a few 10s ( very stable conditions) of meters to 2km over tropical oceans
How does temperature change in the boundary layer?
temperature decreases with altitude
Is a well defined boundary layer always present?
No.
how deep is the stratosphere?
extends from the top of the troposphere to 50 km
how does temperature change in the stratosphere
temperature generally increases with altitude during the summer however is a more complex structure in winter
where is most of the atmopsheric ozone contained
the stratosphere
where is most of the ultraviolet absorbed
the straosphere and can produce a max temp at the stratopause (sometimes more than 0oC)
is the interaction between the stratosphere and troposphere well understood?
No it is limited and poorly understood.
How does pressure change with altitude ( generally)
decreases approximately logarithmically with altitude
Is how warm we feel a very good indicator of air temperature?
No
