Flashcards in Ch 2 - Temperature Deck (44):
What is temperature?
A measurement of particle kinetic energy
Types of temperature transfer?
What is conduction?
- Transfer of heat between molecules
- Gasses are poor conductors
- Earth's surface will heat air on the surface through conduction by day
What is convection?
- Vertical transfer of heat (thermals)
- Thermals carry warm air to higher levels
What is advection?
- Horizontal transfer of heat
- If air conducts heat from the surface, advection can move the warmer air horizontally
What is diurnal variation of temperature?
A daily change in temperature due to the absorption of solar radiation during the day
When is solar radiation at its maximum?
When are diurnal temperatures at their maximum and minimum?
Min: 30 mins after sunrise
What can reduce dirurnal temperature variation?
- Cloud cover (clouds reflect more solar radiation during day / re-radiate more terrestrial radiation at night)
- Wind (turbulence causes warm/cold air to mix)
- Oceans (higher specific heat capacity so takes longer to warm up/cool down)
Convert Celcius to Farenheit?
(C x 9/5) + 32
Convert Farenheit to Celcius?
(F - 32) x 5/9
What is insolation?
The solar radiation which reaches the Earth
Why does only a portion of solar radiation reach the surface?
- Reflected by atmosphere
- Absorbed by ozone
What is an object's albedo?
The amount of solar radiation reflected by it
e.g. snow = high, water = low
Why does temperature decrease with altitude?
- Less atmosphere to absorb and re-radiate terrestrial radiation
- Less terrestrial radiation to absorb
What is mainly responsible for heating the atmosphere?
What is Specific Heat Capacity?
Capacity of an object to absorb heat before its temperature increases
What is an inversion?
Increase in temperature with altitude
What is an isothermal layer?
Layer of constant temperature?
What is thermal inertia?
Time difference between maximum insolation and maximum terrestrial radiation
What is the DALR (Dry Adiabatic Lapse Rate)
-3c / 1000ft OR -1c / 100m
What is the SALR (Saturated Adiabatic Lapse Rate)
-1.8c / 1000ft OR -0.6c . 100m
What is the freezing level?
The altitude at which temperature is 0c
e.g. if -12 at FL100, freezing level will be FL4)
What are inversions?
Where temperature increases with height in warm layers of air
Can significantly affect aircraft climb performance
How can inversions form?
- Surface cooling
- Frontal cooling
- Subsidence (falling air)
What is a surface/radiation inversion?
- Surface of Earth cools air through conduction
- Air above surface layer cools more slowly on its on
- Leads to a low-level warm layer of air
- Only forms over land
What can assist a surface/radiation inversion to form?
- Light or no wind
- Dry air (lower relative humidity)
- Clear skies
- Long nights
- Surface type
What is a valley inversion?
- Surface of a valley cools air around it
- Cooling air sinks down the valley side and pools at the bottom
- As cooling air falls, the cumulative effect is a katabatic wind
- Cold air pools at bottom of valley with layer of warm air above it
- When surface warms up, air can rise up the sides slowly as an anabatic wind
What is a marked temperature inversion?
- Where a temperature difference of more than 10c exists between surface and 1000ft
- Wind sheer can exist at the inversion
What is a frontal inversion?
Where two air masses rub together, the warmer air mass will rise above the colder air mass
What is a subsidence inversion?
- Where a widespread layer of air descends, it compresses and warms adiabatically
- The inversion layer usually rests between 2,000 - 6,000 ft
What is a turbulence inversion?
- Turbulent air mixes warm and told layers of air
- Warm air layer ends up on top
How can inversions be cleared?
- Heating from below
- Strong winds
- Change of weather
What is latent heat?
- Hidden heat transferred when changing states (i.e. solid to liquid)
Latent heat transfers are characterised by a ________ transfer of energy with __________ noticeable change in _________
Is heat absorbed or released when moving from vapour towards solid?
Is heat absorbed or released when moving from solid towards vapour?
What is going from solid to liquid?
What is going from liquid to solid?
What is going from liquid to gas?
What is going from gas to liquid?
What is going from gas to solid?
What is going from solid to gas?