topic 2:weather hazards and climate change Flashcards
what are the three circulation cells and their latitude?
1) Hadley cell- equator to 30 degrees north/south
2) Ferrel cell- 30 degrees north/south to 60 degrees north/south
3) Polar cell- 60 degrees north/south to 90 degrees north/south
what happens at the Hadley cells?
- At the equator warm air rises to 15km, causing low pressure
- This air current divides, cools and moves north and south to from the Hadley cells
- The cooled air sinks at 30 degrees north and south of the equator, leading to high pressure
what happens in the Ferrel cells?
- Some of the cooled air moves back towards the equator as trade winds
- the rest moves to the poles, forming the lower part of the Ferrel cell
what happens in the polar cells?
- at 60 degrees north/south, the warmer air of the Ferrel cells meets the colder polar air.
- The warmer air rises to form the polar cells
- this air travels to the poles, where it cools and sinks, forming areas of high pressure
where does oceanic circulation carry heat to and from?
it carries heat from warmer to colder areas (from the equator to the poles)
how does oceanic circulation move water?
- in the poles water gets very cold and dense so it sinks
- this surface water is replaced by hot water from the equator
what is a glacial period?
a period of colder climate
what is an inter glacial period?
a period of warmer climate
what is the name for the current time period we are living in now?
the Quaternary period
how do Milankovitch cycles cause climate change?
- Milankovitch cycles cause climate change
- these are long term changes to the Earths orbit and position, changing how much solar radiation we receive
how does volcanic eruptions cause climate change?
- in a volcanic eruption dust and ash is ejected into the air
- this acts as a blanket which blocks solar radiation
how does solar radiation cause climate change?
-solar radiation varies causing the Earths temperature to vary
name three causes of climate change?
1) Milancovitch cycles- when the earth gets pulled out of regular orbit
2) solar radiation-radiation levels from the sun varys
3) volcanic eruptions-volcanic ash can deflect sun light away
4) asteroid theory-asteroids can cause dust which blocks radiation
what is evidence for climate change?
1) historical sources- eg diaries
2) ice cores- they trap volcanic ash, microbes and air bubbles that can be used to determine the climate at the time
3) preserved pollen- provides evidence on warm and cold growing conditions
4) tree rings- you can see climate change inside trees as they make yearly growth rings
what is the enhanced greenhouse effect?
when human gas emissions (C02) cause more hot air to get trapped around the Earth causing an increased greenhouse effect
how does the earth receive heat from the sun?
1) Heat energy from the sun passes through the atmosphere and heats up the Earth
2) Much of this energy is radiated back to space
3) greenhouse gases trap some of the heat as it is deflected back as long wavelength radiation
name 4 human causes of climate change?
1) industry- more demand for goods
2) energy- new technology increases demand for electricity
3) farming- population growth causes more demand for food
4) transport- use of cars releases C02
what are the negative impacts of climate change on the environment?
- melting ice sheets causes rise in sea level
- rising sea level may cause soil to get salty and infertile
what are the negative impacts of climate change on people?
- longer periods of drought around the equator so less crops grow
- low lying islands like the Maldives may flood
- photosynthesis at different rates effects food security
what is the medieval warm period?
- a period of warmer temperature in the UK (950-1100)
- because of increased solar radiation, lack of volcanic eruptions and orbital changes
what happened during the medieval warm period?
- more crops
- growing population
what is the little ice age?
- a period of colder temperature in the UK (1600-1685)
- this happened because of increased volcanic activity
what happened in the little ice age?
-the Thames froze
what is the maritime impact on the UK’s climate?
the air reaching Britain contains lots of moisture due t Britain being surrounded by sea
what is the prevailing winds impact on the UK’s climate?
this wind comes from the south west bringing moisture
what is the north Atlantic drifts impact on the UK’s climate?
this ocean current brings warm water north to the UK
what is the atmospheric circulations impact on the UK’s climate?
due to the UK being between the Ferrel and polar cell we get unsettled weather
what is the altitudes impact on the UK’s climate?
the higher the altitude the colder the weather so areas in the UK vary
how do tropical cyclones form?
1) water evaporates from the ocean surface and comes into contact with cold air
2) a column of low pressure develops at the center winds form around the column
3) as pressure in the eye weakens wind speed increases
what are the characteristics of a tropical cyclone?
- low pressure
- rising spiraling air around the eye
- cloud banks called the eye wall surround it