Climate And Weather

Question 1

Briefly explain what is meant by earths atmosphere and its components

Answer 1

Earths atmosphere is held down by gravity. Based on temperature there are 5 layers of
-troposphere
- stratosphere
-mesosphere
- thermosphere
- exosphere
Variations in temperature changes with hight indicate that there are various layers that differ chemically and physically from one another dependent on altitude.

Question 2

Explain the troposphere

Answer 2

-Depth of between 8-16km
- greatest depth over the tropics where warm temperatures create vertical expansion gradually gets thiner towards the poles
- 80% of atmospheres total mass included in troposphere
- where majority of our weather occurs.
- with increasing hight temperatures drop with 6,5 degrees Celsius per 1000m, this is know as environmental lapses rate
- principle gasses: 78% nitrogen, 21% oxygen, argon(0,9%) carbon dioxide (0,03%) and varying amounts of water vapour
-Transition zone known as tropopause

Question 3

Explain the stratosphere

Answer 3

• altitude of 50km above earth
• 19,9% total mass of atmosphere
• very little weather occurs here
• lower portion influenced by polar jet stream and sub tropical jet stream
• first 9km temperature remain constant(isothermal layer)
• as altitude increases pass isothermal layer temperature increases because of a localised concentration of ozone gas molecules
• these O3 molecules absorb UV sunlight creating heat energy that warms up the stratosphere
• this O3 layer(variable concentration) is called the ozone layer(10-50km above earth)
• Ozone layer protects organisms at earths surface from harmful effects of the suns UV radiation
• without this layer life would not exist

Question 4

Briefly explain the mesosphere

Answer 4

-Reaches the coldest temperatures
- 80km above earths surface

Question 5

Briefly explain the thermosphere

Answer 5

-Last layer
- 80km and higher
- extremely high temp(1200 degrees Celsius) generated by absorption of intense solar radiation by O2 molecules
- heat high energy low due to spread out O2 molecules

Question 6

Briefly explain the exosphere

Answer 6

-Upper most region gradually fades into vacuum of space
- air extremely thin almost the same as vacuum of space
It is the planets first line of defence agains meteors , astroids and cosmic rays

Question 7

What is the ozone layer

Answer 7

-A region where the O3 molecule is at its highest.(10-50km)
-Highest concentration(25km)
- shields the earth from harmful effects of UV radiation from the sun
- Ozone layer being depleted by harmful chlorofluorocarbons(CFCs)

Question 8

What would be the result if the ozone layer is severely depleted?

Answer 8

• increased cases of skin cancer
• increase in cataracts and sun burn
• suppression of immune systems in organisms
• impact on crops and animals
• reduction of growth of phytoplankton
• cooling of earths atmosphere and surface climate effects

Question 9

Is the ozone layer recovering ?

Answer 9

Yes at at rate of 1-3% every 10 years

Question 10

How is wind formed ?

Answer 10

Air within the atmosphere moves from place to place when it warms up or cools down

Question 11

What is responsible for the production of weather ?

Answer 11

Winds that move moisture and heat

Question 12

How can wind be defined ?

Answer 12

Air in motion

Question 13

How is wind produced

Answer 13

Wind is produced by the uneven heating of the earths surface by the sun due to different land and water formations that absorb heat unevenly.

Question 14

Can wind flow in any direction and why ?

Answer 14

Yes wind can flow in any direction but in most cases the horizontal flow exceeds the vertical flow

Question 15

What causes wind and wind speeds?

Answer 15

Wind is caused by differences in atmospheric pressure as air moves from a area with higher to lower pressure causing various wind speeds
The Coriolis effect also plays a role die to the earth being a rotating planet meaning air will also be deflected except directly on the equator

Question 16

When are wind speeds at their greatest and why ?

Answer 16

During day time due to the greater spatial extremes in atmospheric temperature and pressure

Question 17

Explain wind formation due to localised temperature differences

Answer 17

In a cold dry climate air has a tendency to sink exerting higher pressure whereas in warmer climates it has a tendency to rise due to being lighter exerting low pressure

Question 18

Explain the Coriolis effect

Answer 18

• Due to the earth spinning winds are forced to follow a curved path
• the Coriolis force exerts opposing pressure gradient acceleration and forces the moving air to change direction
• meaning instead of wind moving from high to low pressure the rotation of the earth causes it to be deflected of course

Question 19

What difference is there in the Coriolis effect in the northern and southern hemisphere on wind ?

Answer 19

In the northern hemisphere wind is deflected right of its path
In the southern hemisphere wind is deflected to the left
Thus southern hemisphere winds blow clockwise and inward at low pressureand counterclockwise and outward at high pressure

Question 20

Explain how the Coriolis effect can be strengthened

Answer 20

The closer the wind is the the north or south Pole the more the strength of the effect increases(greater deflection)

Question 21

What does the Coriolis effect not have an effect on ?

Answer 21

Wind speed and air that has not yet been set in to motion

Question 22

Explain what is atmospheric pressure

Answer 22

The result of the force of gravity acting on air( acts in all directions)
It decreases with altitude

Question 23

Explain global winds

Answer 23

Earths orbit around the sun and its rotation on a tilted axis causes some parts of the earth to receive more solar radiation than others, this uneven heating produces global circulation patterns.

Question 24

How does wind circulate in each hemisphere?

Answer 24

In three distinct cells
Hadley cell
Ferrel cell
polar cell

As warmer air over the equator rises colder air from the poles rush towards the equator to take its place, thus pushing air masses across earth and causing changes in the weather

Question 25

How do global winds effect the weather in south africa ?

Answer 25

Due to movement of wind in the Hadley cell having moved north the cold front systems caused by spiralling low pressure cells formed from the collision of the warm moist westerly wind and the cold dry easterly wind way south of the cape coast reach southern Africa.

In the southern hemisphere summers the wind belts across the globe move south resulting in cold fronts passing way south of the South African landmass

Question 26

Explain the Hadley cell

Answer 26

A) sun heats the air at the equator hot air rises moisture condenses(lots of rain)
B) air transported poleward at high altitude
C) sinks at a 30degree latitude(very dry)
D) moves back to the equator picking up moisture

Question 27

What is wind speed ?

Answer 27

The velocity attained by a mass of air travelling horizontally through the atmosphere

Question 28

What is wind direction? explain how it is determined

Answer 28

It is the direction where a wind comes from and is determined a instrument called a wind vane example a southernly wind blows from the south in a northerly direction

Question 29

How is wind direction named ?

Answer 29

According to the compass direction of the source

Question 30

Explain what is ment by wind chill and what effect it will have on you as a guide

Answer 30

Wind causes the body to loose heat faster, the higher the wind speed the more heat is lost from the body. The temperature your body feels due to wind is called wind chill.
When driving a open game viewer if it is already a cold day your guests will not inly experience the actual temperature but also wind chill factor created by speed if the wind and of the moving car

Question 31

What is air temperature?

Answer 31

Condition of the air with regards to heat and cold

Question 32

Where does the heat of the air come from

Answer 32

Heat is radiated or reflected into the air of the earths surface conducted into it and released as latent heat or condensation

Question 33

What factors influence the temperature of the air ?

Answer 33

• angle at which the suns rays hit the surface(summer=greater angle)
• the length of day( summer longer days=more heat)
• condition of the atmosphere(clouds,dust/!; other factors effects how heat is retained)
  -movement of air(as warm air leaves cold air enters)

Question 34

Explain the summer weather conditions in south Africa and what causes them

Answer 34

-Hot land causes warm air to rise creating a low pressure system over the central parts of the country
- oceans are cooler and have high pressure cells
- on the east coast easterly wind blow over the warm agulhas currentpicking up moisture rising up over the eastern mountains as they cool they form large thunderstorms over the center of the country
- on the west coast the south Atlantic high pressure cell causes south westerly winds over the cold Benguela current the cold water hield moisture meaning little to no rainfall.
During the summer low pressure systems and cold fronts far of shore no influence on the countries weather

Question 35

Explain the winter weather conditions in south africa and what causes them

Answer 35

-Low pressure systems move northwards and brushes the south western cape
-Cold fronts bring rain as they move in a easterly direction.
- each cold front followed by warm north westerly winds causing a drop in pressure and short rain showers
- as the cold front passes high wind speeds recorded and massive thunderstorms
- after front passes winds change direction to south easterly and skies clear
- cold fronts occur every seven days
- originate from south polar front where westerly and cold dry easterly winds blow parallel to each other in opposite directions
The center of the country is dry during winter due to the development of a high pressure cell creating a dense “blanket” preventing moist easterly air from rising over the mountains