The Atmosphere Flashcards
What is an isotherm?
lines joining places of equal temperature?
Briefly explain what a heat equator is?
An isotherm joining places that have the highest temperature at a particular time
What do patterns of isotherms show?
In Jan ,Southern Hemisphere has Summer while Northern Hemisphere has winter
in July ,Southern Hemisphere has Winter while Northern hemisphere has summer
20^ north and south of the equator have high temperatures all year
The Heat Equator is North of the equator in July
The Heat equator is south of the equator in January
What is radiation?
The transfer of heat by means of waves
What is terrestrial radiation
Radiation from the Earth
Long wavelength
Factors that affect Solar Radiation?
Length of the day & night(longer day, longer radiation)
The angle the suns rays hit the Earth(more direct rays means less rays Absorption, Reflection and Scattering)
Parallelism of Earths axis
Define parallelism
The constant alignment of the Earths axis as Earth revolves
When are the solstices?
21 June and 21 December (Longer Day/Shorter Night)
One hemisphere is tilted towards the sun and has summer and the other other hemisphere titled away from the sun experiencing Winter
When are the equinoxes?
20 March and 22 September(Day=Night)
The hemispheres are tilted neither away or towards the sun
Balanced
What is the circle of illumination?
line between light and dark halves of Earth
What is the apparent Migration Of the sun?
Movement the sun makes during the year
Above the Tropic of Cancer in June
Above the Tropic of Capricorn in December
What is radiation surplus and radiation deficit?
Surplus
-More radiation comes in then leaves
Deficit
-More radiation goes out than is received
What is the tri-cellular model of global air circulation?
Model of global air circulation featuring three cells of circulation in each hemisphere?
See exercise book and Pg99
What is the ITCZ?
Inter-tropical convergence zone
Area where winds from twoc cells converge between the two Hadley cells
What are the characteristics of a HADLEY cell?
Warm Air At The Surface Rises Causing Cumulonimbus Clouds
Risen Air Diverges And Moves Poleward
30Degrees North & South cool air subsides
Subsiding air diverges at the surface and air returns to the equator completing the Hadley Cell
What are the characteristics of a Ferrel cell?
Air Subsides at 30^
Warmed Air Moves Poleward
60^ Warm Air Meets Cold Air and converges causing air to rise
Rising air diverges. Some moves equatorward and subsides at 30^ completing the FERREL cell
What are the characteristics of a Polar cell?
Cold air subsides over the pole
Air moves to the equator at the surface and meets warm air from Ferrel cell at 60^
Converging air rises at 60
Air moves poleward completing Polar cell
What is a berg wind and name the conditions necessary for berg winds to occur?
Hot dry wind blowing from to the coast
Conditions
- HP over the interior
- LP over the coastal region
- Air needs to be heated adiabatically(1 Degree per 100m)
Resulting In 1.Very hot dry air 2.Veld fires 3.Dehydration See Exercise Book
What is drought?
When the rainfall received is so low or unreliable that natural vegetation and farming activities suffer
What are the types of droughts?
seasonal/periodic-unpredictable
Disastrous-persistent
Invisible-only seen when there’s a reduction in production over many years
What are the results of drought?
Short term
- Lower agricultural outputs-leads to increased imports and decreased exports
- Water restrictions, jobs lost, high food prices
Long Term
- Desertification
- Increased run-off-increase in soil erosion
What ways can drought be combated?
- Better farming methods
2. Advanced warning systems
What is desertification?
The process in which quality of soil and vegetation cover decreases and land changes to a desert
Land becomes degraded
What are the causes of desertification?
- Increase animals-overgrazing-vegetation cant re-establish-soil exposed to wind and rain
- Population growth-increase demand for wood for cooking-deforestation-vegetation removed-soil exposed
