Climate and weather

Question 1

What are mid-latitude cyclones?

Answer 1

A low pressure cell which develops in the mid-latitudes and travels from west to east.

Converging winds, into the cell, clockwise

Question 2

What is Coriolis Force?

Answer 2

Force that causes the deflection of moving objects due to the rotation of the earth on its axis; greatest at the poles and least at the equator.

Question 3

Mid-latitude cyclones in SA

Where, effects

Answer 3

• develop between 35 degrees S and 70 degrees S (at the polar front)
• southwestern Cape receives winter rainfall = week of cold, cloudy, wet weather

Question 4

Stages of Development of a mid-latitude cyclone

Answer 4

1. Initial Stage
2. Mature Stage
3. Partially Occluded and Occluded Stage
4. Degeneration Stage

Question 5

Initial Stage (MLC)

Answer 5

• bend in polar front
• LP begins to form and winds deflect
• features: winds strengthen and clouds appear

Question 6

Mature Stage (MLC)

Answer 6

• cold and warm front form and divide into a warm sector and a cold sector.
• features: affected by cold sector (on ground) - strong winds, overcast skies and rain.

Question 7

Partially Occluded and Occluded Stage (MLC)

Answer 7

• air is lighter in the warm sector
• cold front overtakes warm front = cold air on ground
• features: cold, nimbus clouds and light rain

Question 8

Degeneration Stage (MLC)

Answer 8

• LP cell disappears and isobars even out

Features: cold, clouds and rain disappearing

Question 9

Cold front conditions

Answer 9

• temperature decreases
• pressure decreases (approaching) and increases (arrives)
• humidity decreases
• winds backing

Question 10

Warm front conditions

Answer 10

• temperature increases
• pressure decreases
• humidity increases

Question 11

What are tropical cyclones?

Answer 11

A low pressure cell that develops over warm oceans between the tropics

Question 12

Characteristics of a tropical cyclone

Answer 12

• violent weather conditions
• strong winds
• huge waves
• heavy rainfall

Question 13

Names of Tropical Cyclones

Answer 13

The first letter of the name tells us how many cyclones have occurred that year.

Question 14

Where do Tropical Cyclones form?

Answer 14

• 30 degrees N and 30 degrees S
• not between 5 degrees N and 5 degrees S as they depend on Coriolis Force
• occur on the east side of continents with warm ocean currents

Question 15

What factors are necessary for the formation of tropical cyclones?

Answer 15

• Hot, humid, unstable air = occur in February to April
• intense LP cell
• Coriolis Force (clockwise)

Question 16

Stages of development of a tropical cyclone

Answer 16

1. Formative stage
2. Immature stage
3. Mature stage
4. Degenerating stage

Question 17

What are the weather condition experienced as a tropical cyclone passes?

Answer 17

• in the eye = hot, humid, calm weather (caused by descending warm air)
• eyeballs = dramatic weather - rapid uplift of air, temperature falls to dew point, heavy rain and thunderstorms

Question 18

Short term effects on tropical cyclones

Answer 18

• strong winds and flooding = destroy infrastructure
• infected water = spread of disease (cholera)
• power/water supply may be cut off
• flooding = loss of crops and livestock

Question 19

Long term effects of a tropical cyclone

Answer 19

• contaminated water supplies (sewerage)

- large-scale soil erosion - floods remove valuable topsoil

Question 20

Strategies that hop to prepare for and manage the effects of Tropical Cyclones

Answer 20

• prediction and warning
• preparing the community (educate on evac routes)
• land use planning
• managing the loss

Question 21

General characteristics of high pressure cells

Answer 21

• descending, dry, warming air = clear skies and sunshine

- air blows out and anti-clockwise

Question 22

What HP cells affect South Africa

Answer 22

SAA - South Atlantic Anticyclone
SIA - South Indian Anticyclone
KH - Kalahari High Pressure

Question 23

Why is the southeaster called “the Cape Doctor”

Answer 23

The strong southeasterly winds blow away the polluted air and has a cooling effect (over the Cape Peninsula and southern Cape)

Question 24

What is a coastal low pressure system?

Answer 24

• moves from west to east around the coast
• autumn and winter
• onshore flow (behind) = clouds and fog
• offshore flow (ahead) = clear, warm weather
  = fire hazard

Question 25

Why is the city warmer than the surrounding rural areas?

Answer 25

URBAN
- built out of artificial substances - absorb more heat
- artificial sources of heat
- polluted air above them - acting as a blanket
RURAL
- heat lost in evaporation

Question 26

What is an urban heat island?

Answer 26

When the central part of a city is warmer than the surrounding suburban and rural areas

Question 27

What is a pollution dome?

Answer 27

A dome-shaped mass of polluted air above a city

Question 28

What are the causes of pollution domes?

Answer 28

• vehicle exhaust

- burning of fossil fuels

Question 29

What are the effects of pollution domes?

Answer 29

• health problems (lung infections)

- buildings and trees suffer (sulphur and nitrogen gas mix with rainwater = acid rain)

Question 30

Strategies to reduce the heat island effect

Answer 30

• change dark surfaces to light reflective surfaces

- ‘greening’ the city (add more parks or water fountains)