Weather & Climate: Theory

Question 1

Troposhpere

Answer 1

Lowest layer.
11 - 12km on average (8km at poles, 17km at equator).
-6.5°C decrease per km altitude increase.
Convection currents allow for weather.
Air pressure 200 - 1000mb.

Question 2

Stratosphere

Answer 2

Troposphere to 50km.
Air pressure 20 - 200mb
High concentration of ozone causes a temperature inversion.
Stable conditions.

Question 3

Mesosphere

Answer 3

From stratosphere to 80 - 90km.
Air pressure 1 - 20mb.
Temp decrease with altitude.
99.9% of the atmosphere's mass is below this layer.
No ozone.

Question 4

Thermosphere

Answer 4

From Mesosphere to space.
Air temperature can rise to 1000°C due to UV radiation, but sparsity of molecules decreases the ‘feel’ of temperature.
Air pressure < 1mb.

Question 5

Latent Heat

Answer 5

Radiation

Question 6

Sensible Heat

Answer 6

Conduction & Convection

Question 7

Wind

Answer 7

The horizontal movement of air on the Earth’s surface. Winds always blow from areas of high pressure to areas of low pressure.

Question 8

The Pressure Gradient

Answer 8

The gradual change of pressure over an area, shown on a weather map using Isobars.

Question 9

Isobars

Answer 9

Lines made by joining points of equal atmospheric pressure together.

Question 10

Hadley Cells

Answer 10

Basis of tropical air circulation.
Responsible for rainforest and desert climates.
0-30°N and 0-30°S, either side of the Inter-Tropical Conversion Zone (ITCZ).
Coriolis effect bends wind to the right, creating NE & SE trade winds.

Question 11

Ferrel Cells

Answer 11

Responsible for mid latitude climates.
30-60°N and 30-60°S.
Warmer air from the tropics meets cold air from the poles at 60°, causing Cool Temperate climates.

Question 12

Polar Cells

Answer 12

60°N+ and 60°S+.

Winds travel outwards from high pressure poles.

Question 13

Subtropical Anticyclone

Answer 13

Meeting of Hadley and Ferrel Cells.

Question 14

Mid-Latitude Depression

Answer 14

Meeting of Ferrel and Polar Cells.

Question 15

Problems With The 3 Cell Model; 5 Factors Which It Ignores

Answer 15

Anticyclones.
Depressions.
Jet Streams.
Trade Winds.
Rotation of the Earth.

Question 16

Impact Of Latitude: Daylight Hours

Answer 16

In the tropics, both day and night last about 12 hours all year round.
The further a place is from the equator, the more varied the lengths of day and night are.
At the poles, the sun doesn’t set during the summer and doesn’t rise during the winter.

Question 17

Impact Of Latitude: Angle Of Incedence

Answer 17

The sun’s rays are concentrated in the tropics because the midday sun remains high in the sky all year round.
As you move further from the equator, the angle of incedence gets lower and the sun’s rays lose energy as they must travel further and are more spread out.
The equator therefore recieves more insolation in a year than the poles.

Question 18

Gyre

Answer 18

A circular pattern of currents e.g. South Equatorial and Benguela (SAtlantic Ocean).

Question 19

Why Are Gyre Patterns So Similar?

Answer 19

They are initiated by the same factors:

• Prevailing wind.
• Atmospheric circulation.
• Coriolis effect.

Question 20

Dominant Ocean Currents

Answer 20

Western sides of gyres e.g. EAC.

Question 21

Weaker Ocean Currents

Answer 21

Eastern sides of gyres e.g. Humbolt.

Question 22

Coriolis Force

Answer 22

The turn of the Earth causes currents to turn to the right in the North, and to the left in the South.

Question 23

Thermohaline Circulation

Answer 23

The formation of ice increases the salinity of water.
Saline water is more dense so it sinks.
This cold water travels from the poles to the equator.
At the equator, less salty water is less dense so it rises.
This warmer water travels back to the poles, completing the cycle.

Question 24

What happens to air when it rises?

Answer 24

It becomes less dense and expands, causing the air temperature to fall.

Question 25

Environmental Lapse Rate

Answer 25

The decrease in temperature due to increase in altitude. The ELR is approximately 6.5°C per 1000m but this varies with air conditions, time and type of surface (land or sea).

Question 26

Dry Adiabatic Lapse Rate

Answer 26

The rate at which an unsaturated parcel of air (no clouds) changes temperature with altitude. The DALR is a constant; 9.8°C per km.

Question 27

Moist (Saturated) Adiabatic Lapse Rate

Answer 27

The rate at which a saturated parcel of air (clouds) changes temperature with altitude. The MALR is a constant; 6°C per km.

Question 28

Weather

Answer 28

The atmospheric conditions such as wind and rain experienced on a day to day basis.

Question 29

Climate

Answer 29

The average weather experienced over a long period of time (usually 30 years).

Question 30

Embryonic Depression

Answer 30

Depressions form where cold polar air and warm tropical air meet - this area is called the polar front.

Cold air forces the warm air upwards, creating a ‘kink’ in the air mass.

Question 31

Mature Depression

Answer 31

The cold front moves faster than the warm front, so winds spiral around the depression.

Pressure falls in the centre of the depression as the air rises rapidly.

Question 32

Decaying (Occluded) Depression

Answer 32

As the cold front catches up with the warm front, an occluded front is created where the air stops rising. This increases the pressure in the center of the depression which subsequently decays.

Question 33

Depressional Weather: Approach

Answer 33

Warmer air rises above cold air, forming cirrus clouds. No rain, but temperatures fall due to cold air mass (PMAM in UK).

Question 34

Depressional Weather: Passing Warm Front

Answer 34

Stratus clouds produce continuous light rainfall. The warm air increases the temperature by between 2-5 degrees, depending on the season (higher increase in Winter).

Question 35

Depressional Weather: Warm Sector

Answer 35

Here everything stabilises; rain stops, temp is stable and wind speed decreases, clouds clear and pressure is steady.

Question 36

Depressional Weather: Passing Cold Front

Answer 36

Steeper gradient of cold air pushing under warm air forces air upwards, creating cumulonimbus clouds. Heavier rain and higher wind speeds. Temperature begins to decrease again.

Question 37

Depressional Weather: Behind Cold Front

Answer 37

Cumulus clouds keep raining, but not as heavy, temperature returns to normal.