Ch 2 - Heating Of The Atmosphere

Question 1

Temperature Conversions

Answer 1

C -> F F = 32.0 + 5/9(C)

F -> C C = 9/5(F) -57.6

C -> K K = C + 273

Boiling 100C or 212F or 373K

Freezing 0C or 32F or 273K

Question 2

Stevenson Screen

Answer 2

Measures Temp and Humidity

1-2m (roughly 4ft) above the ground

Question 3

Conduction

Answer 3

Heat transfer through contact (air is a poor conductor)

Immediate air above the surface of earth it is heated up this way

Question 4

Convection

Answer 4

Vertical movement of air (parcels)

Heat -> Less Dense -> Rise up
Cool -> More Dense -> Sink

(*Lava Lamp)

Question 5

Forced Convection

Answer 5

Mountain or any object that forces air up (orographic lifting) terrain -> high to low pressure

Question 6

Mechanical Convection

Answer 6

Rotors
- Coming down the lee side of a mountain, due to friction, the air comes back up on itself, forcing to rotate

Creates turbulence

Parcels of convection rotors

Can happen when wind interferes with normal convection

Question 7

Radiation

Answer 7

Heat transfer by the absorption of long wave radiation

• Sun gives out short wave radiation (DOES NOT HEAT UP ATMOSPHERE)

Long wave Radiation is what the earth gives out after being heated up by the SWR from the sun. Known as Terrestrial Radiation which heats up the earths atmosphere

Question 8

Latent Heat

Answer 8

Hidden Energy from state change (solid-> liquid)

Sublimation

Must have a nuclei - impurity in the atmosphere

Dumps excess energy heat -Latent heat released into surround atmosphere (no rise/decrease when going from ice to gas)

Latent heat released and surrounding temp increases when going from gas to ice.

Question 9

Advection

Answer 9

Heat transfer by horizontal movement of air

*Wind - Low level due to pressure gradient

Question 10

Insolation

Answer 10

Amount of solar radiation energy being absorbed per unit area over time

• Less at the poles as they are at an angle to the radiation and snow/ice sheets reflect them
• More at EQ - Concentrated amount

3 Main things: Latitudes, season and time of day

Question 11

Earths’ Axis and Orbit

Answer 11

23.5 Degrees tilted

Elliptical Orbit

Anti-clockwise orbit

Question 12

Perihelion

Answer 12

Roughly 4th of Jan (N. Hemisphere winter)

- 91 millions miles away from the sun (closest it gets)

Question 13

Aphelion

Answer 13

4th July (N. Hemisphere Summer)

95 Million miles away from the sun (furthest away)

Question 14

Earth’s Spin

Answer 14

Anti-clockwise

15.04 degrees per hour

Question 15

Equinox

Answer 15

When the earths EQ passes through the centre plane of the sun

23rd September
21st of March

Question 16

Solstices

Answer 16

When the sun reaches its most northerly or southerly excursion relative to the earths EQ

21st of December
21st of June

Question 17

Declination

Answer 17

Angle of the star (Sun) relative to the earth’s EQ

EQ - The Celestial EQ

Question 18

Surface Temperature Variations

Answer 18

Large land masses have potentially large temperature variations due to the low specific heat of land

Sea temperatures remain fairly constant throughout the year

Impacts; Sea currents and Global winds (*Gulf Stream)

Question 19

Heat

Answer 19

The Energy Required to Drive the Activity

Question 20

Temperature

Answer 20

Measure of the heat of energy associated with movement and collisions of molecules

Question 21

Calorie (Cal)

Answer 21

Heat needed to raise 1g of water by 1 degrees C

Question 22

Specific Heat

Answer 22

Ratio of heat needed for some temperature rise

• Water needs 1 cal to raise 1g by 1C

(* Hence sea temp. stays relatively constant)

Ice = 0.5 
Rock = 0.25

Question 23

Diurnal Variation

Answer 23

The daily temperature changes

• Hottest part of the day is 2-3pm (2-3 hours after mid day
• Coldest time of the day is roughly 30 minutes after sunrise (dawn)

Question 24

Factors that affect diurnal variation:

Answer 24

Wind - Stronger wind = less temperature fluctuations

• Day time temp = cooler as cool air being dragged down by mechanical convection from higher layers
• Night - temp doesn’t drop as much as it brings warm air in from layers above

Cloud - more cloud = Less SWR = Less surface temp

• Keeps LWR (terrestrial) in at night = Increased surface temp
• over cast = colder days, warmer nights
• clear sky = warmer days, colder nights

Question 25

Low Clouds

Answer 25

Thicker, More moisture Impact diurnal variation more than high level, whisky clouds

Question 26

Temperature Inversions

Answer 26

Temperature increases with altitude Mid Level inversion Low Level inversion (nocturnal surface inversions) Isothermal layer (stays at a constant temp with altitude)

Question 27

Ground Inversion (Nocturnal / Radiation Inversion)

Answer 27

At night, ground cools, through conduction the first couple of layers of air heat up to about 500ft (can start on surface), then gets trapped by the warmer air sitting on stop of it. This creates the inversion. Layer of smog or impurities sitting below the warmer air. Only forms in very light wind leading to FOG, Stratus (St) or Stratocumulus (Sc) cloud, on or beneath the inversion. With moderate wind the fog can be lifted. As the air is cooled, it may reach the Dew point at which the air becomes 100% saturated with moisture. (100% Relative Humidity) If temp drops even lower and the moisture condenses, it leads to clouds suspended in the air or Radiation Fog on the ground.

Question 28

Valley Inversion

Answer 28

Same process as a Ground Inversion (Radiation or Nocturnal Inversion). - Ground cools, air immediately on top of the ground cools and condenses, causing it to sit at the bottom of the valley with the warmer air sitting on top. It can cool to the Dew Point which would cause the moisture in the air to condense - lead to Fog, Stratus or Stratocumulus clouds In cooler air, there is poor visibility but better aircraft performance because of the cooler dense air. Warmer air = good vis. But bad aircraft performance

Question 29

Subsidence Inversion

Answer 29

Only happens in a High Pressure System - Warm air column descends (subsides) on cooler air which gets trapped beneath it (along with impurities) at roughly 2-3000ft creating a friction/boundary layer where the impurities get trapped. The subsiding air gets heated by compression. Column or air diverges (moves out from the centre as it has nowhere else to go) Clear sky's, with poor visibility. Summer - happens quite a lot, massive high pressure sits on top

Question 30

Frontal Inversions

Answer 30

Red lines with semi circles are warm fonts Blue lines with triangles are cold fronts Both take with them inversion layers Between the lines is warm tropical air (warm sector) Polar air sits behind the warm/cold fronts ``` mP/T = Maritime Polar/Tropical cP/T = Continental Polar/Tropical ```

Question 31

Tropopause Inversion

Answer 31

The isothermal layer sits between 11km and 20km - Staring point is the top of the isothermal layer in the stratosphere - Very stable air above it - Most hot air wont manage to break through the tropopause