Atmospheric Circulation and Climate Change (1) Flashcards
What causes differences in air pressure in the atmosphere?
Differences in Temperature
How is the Earth’s surface heated - what is this called?
The Sun heats up the Earth’s surface - called Insolation
Which part of the Earth’s surface is heated the most?
The Equator receives the greatest amount of insolation (solar radiation heating the Earth)
Which direction to winds blow in (in terms of pressure differences)?
Winds blow FROM areas of high pressure TO areas of low pressure
Name the 3 atmospheric cells
Hadley
Ferrel
Polar
Explain the stages in which the atmosphere is circulated globally
(1) The Earth’s surface is heated by the sun, yet the equator is heated the most. This causes the warm air to rise, forming clouds as it condenses at higher altitudes
(2) The cool, dry air then moves towards 30 degrees N/S of the equator, creating a system of high pressure. The cool air sinks, which causes few clouds to form, so little rainfall is experienced
(3) The cool air sinks to the surface, generating surface winds which either move back to the equator (as trade winds) or move to the poles (as westerlies)
(4) The trade winds will meet at the equator and will be heated, so form clouds again
(4) The less dense, warm westerlies will meet the cold polar air at around 60 degrees N/S of the equator, so will rise above it, forming clouds to fall as frontal rain
(5) The winds either move back towards the equator or move closer to the poles. At the poles, the cool air sinks, creating high pressure, moving as surface winds to the equator
What is Frontal rain?
Frontal rain is rain that forms when warm air masses and cold air masses meet
How do pressure systems cause variations in climate in Arid areas?
Sinking air from the Hadley and Ferrel cells meeting causes high pressure and prevents rainfall since little/no clouds are formed
This means that arid areas are located around 30 degrees N/S of the equator
Temperatures are hot/warm and very dry
How do pressure systems cause variations in climate in Tropical areas
Rising air from the 2 Hadley cells meeting causes low pressure and lots of rainfall, since lots of clouds are formed
Temperatures are hot all the time and rainfall is very high
How do pressure systems cause variations in climate in Polar areas
Sinking sir from the Polar cells creates an area of high pressure at the poles
Temperatures are low all year round and there’s very little rainfall
Name the Natural causes of Climate change
Orbital Motion
Volcanic activity
Solar Output
Asteroid Collisions
Name the Evidence for Natural Climate change
Tree Rings
Ice Cores
Historical Records
Name the Human activities enhancing the Greenhouse effect
Energy
Industry
Farming and Deforestation
Transport
Name the evidence that Human activity is causing Climate change
Increasing global temperatures
Rising sea levels: eustatic sea level rise and thermal expansion
Melting ice caps
Extreme weather events
Explain how Farming and Deforestation has an impact on the Greenhouse effect
(1) Farming cattle releases more methane into the atmosphere (eg by cows passing wind)
(2) Rice paddies, release methane when flooded
(3) Farmers need to clear space for farming - deforestation. This means less CO2 is absorbed by plants, so more is present in the atmosphere
Explain how Transport has an impact on the Greenhouse effect
(1) Cars and other vehicles release harmful pollutants into the atmosphere (eg NOx’s)
(2) As countries develop, more people can afford vehicles
(3) This increases congestion levels, so engines are running for longer periods of time, releasing more pollutants into the atmosphere
Some vehicles are reliant on fossil fuels (eg petrol, diesel)
Explain how Energy has an impact on the Greenhouse effect
A lot of people rely on fossil fuels to provide their energy, releasing more greenhouse gases into the atmosphere when they are burnt
Explain how Industry has an impact on the Greenhouse effect
(1) Most industry and manufacturing uses a lot of energy
(2) Some industrial process release greenhouse gases
(3) Industrial waste may end up in landfill sites where it decomposes, releasing methane
Explain the Greenhouse effect
(1) Short-wave radiation from the Sun heats up the Earth’s surface
(2) The Earth emits some of this radiation back into space as infrared radiation, but some is absorbed by greenhouse gases (such as CO2, CH4, H20)
(3) These then emit the gases in all directions, heating the Earth’s surface even more
The longer the greenhouse gases remains in the atmosphere, the more they contribute to global warming
Explain how Tree Rings provide evidence for natural climate change
- Every year, trees produce rings on their trunks
- The thicker the rings, the hotter the temperatures they grew in
- Scientists can compare the thickness of current tree rings with older ones to see what the climate was like each year
Explain how Ice Cores provide evidence for natural climate change
- Ice sheets are made up of layers of ice - one layer is formed every year
- Scientists drill into these to get ling cores
- By analysing the gases (eg CO2) trapped in layers, they can tell what the temperature was
- More CO2 will result in higher temperatures
Explain how Historical Records provide evidence for natural climate change
- Records such as diaries and paintings can extend the record of climate change
- Diaries can show what the weather was like eg by giving the number of days of rain
- Paintings of fairs and markets suggest that winters in Europe were colder (500 yrs ago)
Explain how Volcanic activity is a cause of natural climate change
- Major volcanic eruptions eject large quantities of material eg ash into the atmosphere
- Some particles reflect the Sun’s rays back out to space, cooling the Earth’s surface
- May cause short-term changes in climate - decreasing temperatures
Explain how Asteroid collisions are a cause of natural climate change
- Collisions with Earth’s surface can eject huge amounts of dust into the atmosphere
- These particles prevent the Sun’s energy from reaching the Earth’s surface
- Causes global temperatures to fall (possibly for several years)
