Chapter 2 - Temperature And Heating Flashcards
What is specific heat capacity?
The energy it takes to heat up a material by 1 Kelvin. J/K
What is the specific heat capacity of water at 25degC?
4.2J/K
What is the specific heat capacity of earth/rock?
0.8J/K
In what season is the sea warmer than land and why?
Winter because the land radiates its heat energy faster than water.
In what season is land warmer than the sea and why?
Summer because it takes less energy to heat up the earth than it does the sea.
On a clear day how much solar radiation penetrates through the atmosphere and what happens to the rest?
85% the rest (short wave UV) is absorbed by the ozone layer.
What kind of radiation does water vapour absorb in the lower atmosphere?
Long wave IR
What is the main source of atmospheric heating and why?
Terrestrial radiation.
This produces long wave radiation, after absorbing short wave radiation, which can be absorbed by gases and is mostly absorbed at the surface.
What is diurnal variation of surface air temperatures?
The daily variation of surface air temperatures due to the sun.
At approximately what time does the minimum surface air temperature occur and why?
06:30, 30 mins after sunrise.
This is due to the outgoing terrestrial radiation being higher than incoming solar radiation from sunrise until 6:30.
At approximately what time does the maximum surface air temperature occur and why?
15:00, 3 hrs after noon.
The incoming solar radiation remains higher than the outgoing terrestrial radiation until 15:00.
At what altitude does diurnal variation stop having significance?
3000ft
How does surface type affect diurnal variation?
The higher the specific heat capacity the lower the diurnal variation.
Eg water at 4.2J/K had a much lower diurnal variation than earth at 0.8J/K
How does cloud cover affect diurnal variation?
It insulates and re radiates heat. This means that constant cloud cover during the day will decrease both the min and max surface temperature.
How does wind affect diurnal variation?
It reduces both the minimum and maximum temperatures by mixing the surface air with the air above it.
What is insolation?
The solar radiation which reaches the earths surface.
What is albedo?
The reflectivity of a surface.
The lower the albedo of a surface the more heat is absorbed and thus thermals occur.
What is an inversion.
A layer of the atmosphere where lapse rate is reversed.
Name 4 different types of inversion.
Surface cooling
Frontal
Subsidence
Turbulence
How does a surface inversion occur?
At night the earth cools faster than the air. The cool earth then conducts heat from the air and cools it so that is it colder than the air above it.
What factors aid in the formation of an inversion?
Light/no wind Dry air Clear skies Long nights Air being over land
What effects do inversions have on weather?
The warmer part acts as a weather lid, suppressing convection and trapping air below. This traps pollutants and thus leads to poor visibility.
How is an inversion cleared?
Air mass is heated from below.
