Meterology Flashcards
What is the role of the ozone?
Absorbs short wave solar radiation. it too acts as a heat source in the atmosphere.
What are the characteristics of the troposphere?
- Lowest layer in the atmosphere
- In this layer temperature decreases with height.
the temperature decrease is about 2 degrees per 1000ft or 0.65 degrees per 100m (or 0.65 degrees per km.) - Layer is 11km thick
- Lapse rate decreases to less than two degrees per km (1.98 degrees.)
What are the characteristics of the tropopause?
- Height where temperature no longer decreases with altitude > air is ‘stable’
- Acts as a barrier no air can rise through it.
What are the heights of the tropopause? Why are they like this?
-8-10km over the poles and 16-18km over the equator. (reaches the tropopause)
At the poles the air is much cooler so the air is retained closer to the surface.
-At the equator, the air expands and ‘pushes’ the tropopause outwards and away from the surface (in the latitude.)
When is the height of the tropopause lowest and at its highest?
Highest height at summer. Lowest height at winter.
‘the height is determined by the temperature of the air in the troposphere near the surface.’ > the warmer the air the higher the tropopause the colder the air the lower the tropopause.
Where are the tropopause breaks?
They are where fast moving upper air currents (jet streams) found?
Ferrel and Polar cells is knows as a ‘break or fold’
30 degrees and 60 degrees.
what is the average surface temperature? How much does the temperature decrease by per height.
+15 degrees
2 degrees per 1000ft
1km = 3280ft
What are the characteristics of the tropopause?
- Temperature increases with altitude
- Temperature is constant with with height (isothermal) > as height increases so does the temperature.
What causes the increase in temperature in the stratosphere?
Its caused by the absorption of the suns ultraviolet (UV) by the ozone layer. Ozone layer is found 25km AMSL.
why is the stratosphere a good place to fly?
- Stable and generally uniform > no convection.
-Avoids hazards. - Cold dry conditions with no active weather and no convective turbulence.
What are the characteristics of the mesosphere?
- Temperature decreases with height > 0- 90 degrees.
- Mesosphere extends from 50km to 80-90km.
What dare the readings of a radioscope measure?
Temperature
Pressure
Humidity
Tracks wind but does not measure.
What’s terrestrial radiation?
When the earth absorbs solar radiation it heats up. The atmosphere is heated up by the surface.
What is conduction?
Transfer of heat by direct physical contact which occurs at the bottom few thousand feet of the atmosphere.
What is convection?
Vertical transfer of heat upwards and downwards.
What is Advection?
Horizontal transfer of heat.
What is Turbulence?
Chaotic interference between two airflows. this is the changes in heat between the surface and upper layers.
What is insolation?
Short wave energy that penetrates through the atmosphere and reaches the earths surface
What is albedo? What factors affect it?
Albedo is incident light reflecting by the surface.
Factors:
Seasons
Latitude
Surface type
Reflectivity of surface
Reflectivity of cloud
What are Greenhouse gases?
-Absorb terrestrial radiation emitted from surface
-Maintain habitable temperatures
-Absorption causes global temperatures to rise.
-Contains water vapor, carbon dioxide, hydrogen, methane, ozone and carbon monoxide.
What are the effect of clouds?
Daytime: Solar radiation (insolation)
Nighttime: terrestrial radiation > re-radiates the atmosphere
How is energy transferred through the atmosphere?
Terrestrial/thermal/infrared radiation
Conduction
Convection
Advection
Latent heat
what are the causes of wind
Mixing of warmer layers with cooler layer > causes turbulence.
What is the polar stratospheric cloud called?
Nacreous
What is the standard mesosphere called?
Noctilucent
What are the densities at different feet?
10,000ft = 0.903kg/m^3
22,000ft = 0.602kg/m^3 (when density is half.)
40,000ft = 0.302kg/m^3
What are the pressures at different feet?
Ascending pressure (hpa) = descending feet (ft)
100hpa = 50,0000ft
200hpa = 40,000ft
300hpa = 30,000ft
400hpa = 20,000ft
500hpa = 10,000ft
Whats a subsidence inversion?
- Common in high pressure area
- Descending dry air warms faster than static environmental air
What is a Frontal layer?
Warm, less dense, air flows up and over cooler, denser air
Whats a friction layer?
Created by turbulent mixing modifying the surface layer lapse rate.
Whats a valley inversion?
Formed at night when colder, denser air sinks, displacing warmer air apwards
What’s ITCZ
Intertropical convergence zone
What happens in a high pressure area?
- Upper level convergence
- Sinking air
- Adiabatic warming
- Surface level divergence (as it cannot go any further so it expands horizontally.)
What happens in a low pressure area?
- Surface level convergence
- Rising air
- Adiabatic warming
- Upper level divergence (as it cannot go any further past tropopause so it expands horizontally.)
Absolute humidity is?
The amount of water vapour that a given quantity of air holds
What is the humidity mixing ratio?
The number of grams of water vapour per kilogram of dry air
Saturation is?
When a sample of air contains the maximum amount of water vapour that it can support at a given temperature and pressure
Relative humidity is?
The amount of water vapour in a sample of air compared to how much that sample of air could contain.
What is the diurnal relative humidity?
increases with a decrease in temperature
relative humidity is inversely proportional to temperature.
What is the ELR, DALR & SALR
DALR = 3 deg/1000ft or 1deg/100m
ELR = varies
SALR = 1.8 deg/1000ft or 0.6 deg/100m
What is it called when a force drives an area of high pressure to an area of low pressure?
Pressure gradient force (PGF)
what are isobars?
Lines of equal pressure
What affects density the most and what affects density the least?
Most - Pressure
Least - Humidity
Air is saturated when?
It cannot hold anymore water vapour and it begins to condensate (after it meets the dew point)
What is disposition?
when gas turns into a solid
What is sublimination?
when solid turns into a gas
What is latent heat in melting
Latent heat is absorbed from the solid surroundings and stored in liquid water.
What is latent heat in evaporation/vapourisation?
Adding heat gives the energy to break apart H2O molecules resulting in latent heat being taken from its surroundings
What equipment measures humidity?
Digital Hygrometer
Psychrometer
What is the cumuliform cloud base?
Cloud base (ft) = temperature - Dew point) x 400
What triggers thunderstorms?
Convection, orthographic uplift, frontal uplift, TURBULENCE
The earth has 3 global pressure system cells; where are they located?
Northern hemisphere
1st Polar (0-30 deg) 8-10km over the tropopause
2nd Ferrel (30-60 deg) 11km tropopause height
3rd Hadley (60-90deg) 16-18km troposphere height
Southern Hemisphere
1st Hadley (90-120 deg) 16-18km troposphere height
2nd Ferrel (120-150 deg) 11km tropopause height
3rd Polar (150-180 deg) 8-10km over the tropopause
ITCZ
CB’s!!
What are the columbs in the met form 214
1st column = Altitude in 1000s ft
2nd/3rd column = Wind direction and speed
4th column = Temperature
Characteristic of Microburst
A downflow of cold air.
Lasts 4min and 4km (4/4)
Radiation Inversion
Often occurs at night when temperature leaves the surface and increases with height. Remember no blanky on the earths surface
What measures the
Explain terrestrial radiation
Short wave insolation penetrates through the atmosphere
Long wave terrestrial radiation absorbed by the atmosphere
Precipitation types and sizes
Cloud/water droplets: 0.02mm diameter
Drizzle (DZ): Diameter less than 0.5mm
Snow grains (SG): less than 1mm
Snow pellets: 2 – 5 mm
Small Hail (GS): < 5mm
Hail (GR): Hail 5 – 50mm
What happens to altitude in hot and cold temperatures?
When the air is warmer (higher pressure) the altitude will be higher than ISA (SAFE)
When the air is colder (low pressure) the altitude will be lower than ISA (DANGER -> HIGH TO LOW, LOOK OUT BELOW! )
