Book15 Flashcards
What is the atmosphere?
A blanket of gases surrounding Earth, held in place by gravity.
What percentage of the atmosphere is nitrogen?
78.08%
What percentage of the atmosphere is oxygen?
20.95%
What percentage of the atmosphere is argon?
0.93%
What gas helps filter out harmful UV radiation?
Ozone (O3)
What are the two main greenhouse gases mentioned?
Water vapor and carbon dioxide
How much would Earth’s temperature fall without greenhouse gases?
Around 33°C
What are the five vertical zones of the atmosphere?
Troposphere, stratosphere, mesosphere, thermosphere, exosphere
What is the boundary between atmospheric zones called?
A ‘pause’
In which atmospheric layer does most weather occur?
Troposphere
How much does temperature drop per 1,000 meters in the troposphere?
6.4°C
What causes the temperature increase in the stratosphere?
Concentration of ozone absorbing UV radiation
What is the height of the tropopause at the equator?
Up to 16 km
What is the height of the tropopause at the poles?
About 8 km
What is the global heat budget?
The balance between energy received and radiated by Earth
What percentage of incoming solar radiation is reflected back to space?
32%
What is albedo?
The intensity of light reflected from an object
What percentage of incoming solar radiation reaches Earth’s surface?
55%
What percentage of incoming solar radiation is absorbed by Earth’s surface?
49%
What type of radiation does Earth emit?
Infrared (long-wave) radiation
What is terrestrial radiation?
Long-wave radiation emitted by Earth
What is the solar constant?
1366 joules per second per square meter
Between which latitudes is there an energy surplus?
35° North and 35° South
What is the latitudinal or global temperature gradient?
Temperature reduction from Tropics to polar regions
What percentage of thermal energy is redistributed by atmospheric circulation?
75%
What percentage of thermal energy is redistributed by ocean currents?
25%
What are the three cells in the three-cell model of atmospheric circulation?
Hadley, Polar, and Ferrel cells
What is the Coriolis effect?
Deflection of winds due to Earth’s rotation
In which direction are winds deflected in the northern hemisphere?
To the right
In which direction are winds deflected in the southern hemisphere?
To the left
What type of cell is the Hadley cell?
Thermally direct cell
What type of cell is the Polar cell?
Thermally direct cell
What type of cell is the Ferrel cell?
Thermally indirect cell
What are trade winds?
Surface winds blowing towards the equator in the Hadley cell
What is the ITCZ?
Intertropical Convergence Zone
What causes the ITCZ to move throughout the year?
The apparent movement of the Sun
What are Rossby waves?
Long, variable velocity waves in the upper troposphere
What causes Rossby waves?
Temperature variations, topographic forcing, and Coriolis effect
What are jet streams?
Narrow bands of fast-moving air in the upper atmosphere
At what height is the polar jet stream typically found?
7-12 km
At what height is the subtropical jet stream typically found?
10-16 km
What direction do jet streams generally travel?
West to east
What is convergence in atmospheric circulation?
Air moving inwards at the surface
What is divergence in atmospheric circulation?
Air spreading outwards at the surface
What are the three main wind groups in the global surface winds model?
Trade winds, mid-latitude westerlies, and polar easterlies
What wind blows from approximately 30° to 60° North and South?
Mid-latitude westerlies
What wind blows from the Arctic and Antarctic?
Polar easterlies
What is the thermal equator?
The belt of maximum surface heating
What two air masses converge over Africa in the ITCZ?
Tropical Maritime and Tropical Continental
What is the origin of the Tropical Maritime air mass over Africa?
Atlantic Ocean
What is the humidity level of the Tropical Maritime air mass?
65-82%
What is the origin of the Tropical Continental air mass over Africa?
Sahara Desert
What is the humidity level of the Tropical Continental air mass?
10-18%
What wind is associated with the Tropical Continental air mass in Africa?
Harmattan
In which month is the ITCZ typically at its northernmost position in Africa?
July
In which month is the ITCZ typically at its southernmost position in Africa?
January
What type of season does the ITCZ bring when it moves over an area?
Wet season
What type of season occurs when the ITCZ moves away from an area?
Dry season
What is the Sahel?
A semi-arid region bordering the southern edge of the Sahara Desert
How many vegetation types are estimated to be in Ghana’s rainforests?
Over 4,500
How many plant species are estimated to be in the Sahara Desert?
About 500
What is the dominant agricultural practice in the Sahel?
Nomadic herding
What river provides water to the Sudan Savanna and Sahel in Mali?
Niger River
What is the annual rainfall in northern Mali?
203 mm
What is causing the Sahara Desert to move southward?
Poor land management and removal of trees
What are ocean gyres?
Large circular loops of ocean currents
In which direction do gyres rotate in the northern hemisphere?
Clockwise
In which direction do gyres rotate in the southern hemisphere?
Anticlockwise
What is the average speed of water at the extremities of a gyre?
About 5 km/h
What is the Antarctic Circumpolar Current also known as?
West Wind Drift
What is thermohaline circulation?
Deep ocean currents driven by temperature and salinity changes
How much heat energy does thermohaline circulation move towards the poles?
10¹⁵ W
How long does it take for thermohaline circulation to turn over all deep ocean water?
700 to 1,000 years
What happens to water density when it is warmed?
It decreases
What happens to water density when salt is added?
It increases
What is Walker circulation?
A theoretical model of air movement in the tropical troposphere
What is a Walker cell?
A self-contained circulation of air in the tropics
What is El Niño?
A warming of the central and eastern tropical Pacific
What happens to trade winds during El Niño?
They weaken or reverse direction
What is La Niña?
A cooling in the eastern tropical Pacific
What happens to trade winds during La Niña?
They strengthen
How often do El Niño and La Niña events typically occur?
Every 2 to 7 years
How long do El Niño and La Niña episodes usually last?
9 months to 2 years
What happens to tropical cyclone activity in the North Atlantic during El Niño?
It is reduced
What happens to the Indian monsoon during La Niña?
Rainfall increases
What happens to fish stocks in the eastern Pacific during El Niño?
They decrease
What happens to fish stocks in the eastern Pacific during La Niña?
They increase
What type of weather does El Niño bring to the British Isles?
Mild, wet, and windy weather
What happens to convection in the western Pacific during El Niño?
It reduces
What happens to convection in the western Pacific during La Niña?
It increases
What is the effect of El Niño on the Sahel region of Africa?
It correlates with droughts
What happens to precipitation in Peru during El Niño?
It increases, often causing floods
What happens to precipitation in Peru during La Niña?
It decreases https://chatgpt.com
What is the effect of La Niña on tropical storms in Australia?
It increases their number and severity
What happens to upwelling of nutrients in the eastern Pacific during El Niño?
It is reduced
What happens to upwelling of nutrients in the eastern Pacific during La Niña?
It increases
