Climate Hazards Flashcards
Define Solar Insulation
amount of suns energy
How is solar insulation distrubuted
Intense at equator, concentrated dispertion
At poles wide distribution so less intense
How is heat redistrubuted
Ocean currents and circulation cells
What causes circulation cells
differences in pressure
What do ocean currents do
ocean currents bring warm water to colder places by winds
Define wind
Movement of air from high –> low pressure.
Describe a circulation cell
Sun heats surface causing air to rise and expand creating low pressure and rainfall
After it reaches high enough latitude it cools and sinks back to earth to create high pressure and dry conditions
What happens at the Hadley Cell
air reaches about 30 north and south the air cools and sinks forming the subtropical high-pressure zone
Creating an area of little cloud and low rainfall; deserts
What direction do the northeast trade winds go
Winds flow to the right and in northern hemisphere
What direction do the south east trade winds go
In the southern hemisphere and flow to the left
What winds do the ferrel cell form
Air on the surface is pulled towards the poles, forming the warm south-westerly winds in the northern hemisphere and north-westerly winds in the southern hemisphere
How does the ferrel cell cause mid-latitude depressions(UK)
westerly winds pick up moisture over oceans and meet cold air at 60 drifted from trhe poles.
Warmer air lighter than cold so it rises causing low pressure at surface; Uk wet and windy weather
What is the polar high caused by the polar cell
at the poles, air is cooled and sinks towards the ground forming high pressure, this known as the Polar high.
What happens to air from the polar high
Drifts to lower latitudes till it meets warmer air at 60 causing a zone of low pressure called the polar front due to its denseness
What is the tricelluar model
Polar cell Ferrel Cell Hadley Cel Hadley Cell Ferrel Cell Polar Cell
What are the bands of pressure
Polar high Sup-polar low Sub-tropical high equatorial low sub-tropical high sub-polar low polar high
Define the ITCZ
The ITCZ is a zone of convergence at the thermal equator where the trade winds meet. It is a low pressure belt and migrates with the changing position of the thermal equator.
Why is the ITCZ not straight
Landmasses being able to heat quickly and sea releases heat over a long time
What impact does the ITCZ have
Seasonal as ITCZ moves up and down
heats area to create low pressure and constant rainfall
How are deserts created
Hot conditions from being near equator but hardly receives rain from ITCZ
Define Jet Streams
Fast moving jets of air moving in the upper atmosphere
>200mph from west–> east in North Hemisphere
What can cause big differences in weather due to jet streams
Jet streams can buckle due to polar wind or tropical wind moving south or north respectively
What do stationary jet streams cause
Bring frequent depressions to the same region
What is an example of ocean curents
example the gulf stream is a warm ocean current driven by westerly winds. In the north atlantic cold,salty water is heavy and sinks. This sets up a convection current which drags surface water down. The current draws warmer salty water over the ocean surfaces from areas near the equator which cools and sinks in the Labrador and Greenland seas to go back to the Equator where it is warmed again
Define radiation
the transfer of heat energy by electromagnetic waves without particles
Define conduction
flow of energy from one particle to another with different temp.
Define sunspot theory
sunspots show the activity of the sun; lots mean more energy
What is evidence for the sunspot theory
Maunder minimum; low sunspots when there was the Little Ice Age
How does volcanic activity affect the climate
eruptions eject ash; circulated by jet streams
ash = global dimming
less heat –> less rainfall –> less evaporation
Define Milankovitch Cycles
They influence the solar insulation the Earth receives, greatest effect when the 3 cycles combine every 100,000 years
What are the 3 Milankovitch Cycles
(Stretch) Eccentricity - 100,000 years. Turn more elliptical
o –> 0
(wobble) Precession - 26,000
(tilt) Obliquity - 41,000 years
How do asteroids affect the climate
1 km sized asteroids strike Earth every 500,000 years
Blocks sun with debris and ash uplifted effects would last 5-10 years
define quaternary period
current geological peiod which begun 2.6 million years ago.
What is the holocene
warm priod which began when the ice caps melted in the northern hemisphere 12,000 years ago
Define proxy measure
indirect measure of a trend when there is no absolute evidence
How do we use ice cores as evidence for past climates
Best evidence for past climates goes back as far as 800,000 years
Layers contain air bubbles with O2 and CO2 isotopes use these to calculate accurate temp.
Define dendrochronology
Using tree rings to date past events
Why is dendrochronology reliable
Warm years trees have wide rings
Cold years have narrow rings
Records can go back 10,000+ years
How is Historical sources used to show past climates
Source may report weather or indirectly show the weather at that time. Go back 3,000 years
Why are historical sources not reliable
Biased, fictitious or wrong
Define thermal expansion
water expands when heated
Define the greenhouse effect
natrual warming of the earth as grenhouse gases trap energy from the sun
Define the enhanced greenhouse effect
additional warming caused by humans producing greenhouse gases since 1940
What is the evidence for man-made climate change
- Sea level rise
- warming oceans + bleached coral reefs
- temp. rise
- declining arctic sea ice
- inc. extreme weather events
