CLIMATE AND WEATHER Flashcards
(28 cards)
What is a Berg wind?
Hot, dry winds blowing in from the interior of South Africa to coastal areas in winter.
In which season do berg winds usually occur?
Winter
Explain how berg winds have a negative impact on the natural
environment.
Strong winds can cause soil erosion.
Hot dry winds cause vegetation to dry out.
Friction with dry vegetation and hot wind enhances veld fires.
Hot dry winds decrease soil moisture.
Strong winds will cause the disturbance of the ecosystems.
Discuss how the cold front occlusion is
formed.
Cold air masses move faster than warm air masses (cold air is heavier)
- The cold air undercuts the warm air and cool air ahead of it
- Cold air(front) overtakes(uplifts) the warm front
- Cold air remains on the surface.(2)
Account for the weather associated with the cold front occlusion
Possible thunderstorms – as cold air undercuts warm air forcing it to rise – clouds form resulting in rainfall
- Brings cumulonimbus clouds associated with heavy rainfall.
- Cold dry weather (behind the cold front) – cold air carries less moisture
Explain the development of the cold front occlusion which will lead to
the dissipation of the mid-latitude cyclone.
The cold front which is moving faster undercuts / overtakes the warm front.
The warm air is forced to rise resulting in a narrowing of the warm sector.
The coldest air is found behind the cold front causing the warm air to be uplifted along the cold front
The cool air (in front of the warm front) is completely uplifted.
The system dissipates once the warm air has been displaced and there is only cold air on the surface
What is an inversion layer?
A layer in the atmosphere in which air temperature increases with altitude.
explain how the
subtropical anticyclones influence the climate over the interior of South
Africa during summer.
During summer, the Kalahari high pressure cell is not very well developed as it shrinks and weakens.
The weakened Kalahari high pressure cells allow the inversion layer to lie above the level of the plateau / escarpment.
Warm moist air (from the south Indian anticyclone) is able to reach the interior of the country because of the weakened Kalahari high pressure cell.
The south Indian high-pressure cell, situated over the Indian Ocean,
supplies warm, moist air (rain) because of the anticyclonic circulation.
Divergence of air (NE winds) from south Indian anticyclone onto the
interior brings rain.
Unstable conditions cause air (from the south Indian anticyclone) to rise, condensation to occur and clouds / rain to form.
Because of the weakened Kalahari high pressure cell, less air subsides (less compressed air which heats up).
Cold and dry air diverges (SW) from the South Atlantic high
pressure, bringing cold dry winds towards land.
Ridging of the South Atlantic high pressure diverts moist air from the
Indian Ocean onto the land.
A strong south-easterly from the South Atlantic high ridge brings a
strong onshore wind).
What is a moisture front?
The zone between two air masses with different moisture content.
explain how the summer
location (position) of the high-pressure cells (anticyclones) promotes the
development of line thunderstorms.
A weakened Kalahari High Pressure cell allows vertical rising of air
above the interior.
This encourages increased convergence of air masses from well-
developed High Pressure cells.
The South Indian High Pressure is found more to the east from the land
and further south in summer.
This allows warmer moist air to diverge from the South Indian High
Pressure cell towards the interior.
In summer, the South Atlantic high pressure extends along the south-
east coast of the country.
Cold and dry air diverges from the South Atlantic High Pressure cell to
meet the warm moist air mass from the South Indian high pressure cell
in the interior of the country.
Suggest TWO possible reasons why Tropical Cyclone Freddy intensified
from a category 3 to a category 5 cyclone
Warm ocean surface temperatures in the Indian Ocean (more than
26.5°C).
LP intensified because of warm ocean temperature.
Increased evaporation (over the Indian Ocean).
Increase in the latent heat.
Sufficient distance away from the equator for Coriolis force to take
effect.
Limited friction on the water surface.
What could have caused the rapid weakening of Tropical Cyclone Freddy
when it made landfall
Lack of moisture (source).
Frictional drag with the land surface.
Reduced latent heat.
strategies that the local authorities in Mozambique could
implemented to prepare for the destruction caused by Tropical Cyclone
Upgrading of their early warning systems/tracking/communication
systems.
Evacuation of inhabitants from coastal region.
Mobilise emergency personnel.
Prepare health facilities.
Stockpile food and drinking water.
Ensure a supply of medicines.
Prepare community shelters.
Tide breakers / sea walls to prevent flooding/damage of houses.
Define the term temperature inversion.
A rise/increase in temperature with an increase in height/altitude
