Global atmospheric earth (Topic1) Flashcards
What is wind?
wind is the movement of air caused by the uneven heating of the earth by the sun and the earths own rotation
What is the coriolis effect?
the coriolis effect is that circulating air is deflected towards the right in the northern hemisphere and towards the left in the southern hemishphere
How does air move around the world?
Air rises at the equator, leading to low pressure and rainfall
When air reaches the edge of the atmosphere, it cannot go any further and so it travels to the north and south
As a result, the air becomes colder and denser and falls, creating high pressure and dry conditions at around 30• north and south of the equator
large cells of air are created in this way
Hadley cell
The first cell is called the hadley cell. At the equator, the ground is intensely heated by sun which causes air to rise which creates a low pressure zone
As air rises, it cools and forms thick storm clouds
Air continues to rise until it cannot go any further so it travels to the north and south
As a result, the air becomes colder and denser and falls creating high pressure and dry conditions at 30• north and south of the equator. This is where deserts are found
The hadley cell is then complete. The air completes the cycle and flows back towards the equator.
Ferrel cell
The ferrel cell occurs at 30-60• N&S of the equator
Air on the surface is pulled towards the poles forming warm south westerly winds in the northern hemisphere and north westerly winds in the southern hemisphere
These winds pick up moisture as they travel over the oceans
At around 60•N&S they meet cold air. the warmer air is lighter then the dense cold polar air and so it rises as the 2 meet
The uplift in air causes low pressure at the surface and unstable weather conditions. This determines a lot of our wet windy weather
Polar cell
At the poles, air is cooled and sinks towards the ground forming high pressure (polar high)
It then flows towards the lower latitudes. At about 60•N&S, the cold air mixes wiht the warmer tropical air and roses upwards creating a zone of low pressure (subpolar low)
The boundary between the warm and cold air is called the polar front.
What is an area of low pressure called?
A depression
What does areas of low pressure cause?
clouds and rainfall to form (unsettled weather)
What happens to winds in a depression and how is it shown?
winds are normaly stronger
shown by isobars being closer together
Where do depressions normally form and what direction do they move in?
over the atlantic ocean and are carried across britain by westerly winds and move in an anticlockwise direction
How can we recognise depressions on a weather chart?
the isobars are below 1000mb and are packed closer together
a warm front (red line) is followed by a cold front (blue line)
What is an area of high pressure called?
an anticyclone
What does areas of high pressure cause in summer and winter?
summer: clear skies and a gentle breeze
fine weather
winter: clear skies and colder conditions
What happens to winds in a high pressure area and how is it shown?
less winds as the isobars are further apart
what direction do anticyclones move in?
clockwise
How can we recognise anticlyclones on a weather chart?
isobars are above 1000mb and spread further apart
What lasts longer and anticyclone or a depression?
anticlyclones - 2 weeks
depressions 2-3 days
Order the layers of the earth
inner core
outer core
mantle
crust
Describe the inner core
centre of the earth and is the hottest part of the earth
a solid made up of iron and nickel
temps up to 5500•
Describe the outer core
the layer surrounding the inner core
a liquid layer made of nickel and iron
Describe the Mantle
the thickest section of the earth approximately 2900km
made of semi molten rock called magma
Describe the crust
is the outer layer of the earth
a thin layer between 0-60 km thick
a solid layer and is either continental or oceanic , we live on the crust
What is the athenosphere
the upper part of the mantle is called the asthenosphere
made of semi molten rock called magma
What was originally believed about plate movement?
The earths crust is broken into tectonic plates, it was once believed that convection currents in the mantle caused the plate to move. However it is now recognised to be more complicated than this
what actually causes plate movement?
Mechanism called slab pull and ridge push are believed to move tectonic plates
Ridge push
Is where the new crust formed at the divergent plate margins is less dense than the surrounding crust and so it rises to form oceanic ridges
The older sea floor either side of the ridge slides away and this moves the seafloor apart – moving the tectonic plates
Slab pull
occurs where older denser tectonic plates sink into the mantle at subduction zones
as these older plates sink newer less dense sections of plate are pulled along behind sinking in one place leads to plates moving apart in other places
Conclusion of plate movement theory
therefore instead of tectonic plates moving because of the convection currents, evidence suggests that it is the plates that drive the convection
Natural causes of climate change
orbital changes - milankovitch cycles are variations in the tilt/orbit of the Earth around the Sun, causing natural warming and cooling periods
volcanic eruptions - carbon dioxide is released into the atmosphere during eruptions
Solar output - the amount of radiation omitted by the Sun fluctuates. High level is a radiation lead to an increase in earth temperature
Human causes of climate change
Deforrestation- (cutting down trees) trees absorb CO2. One trees are cut down less CO2 will be absorbed leading to increased concentrations of it in the atmosphere
Burning fossil fuels - when coal, gas and oil are burned, carbon dioxide is released into the atmosphere
Agriculture - increased animal/pastoral farming leads to more methane being released into the atmosphere
Dumping waste in landifill - as waste decomposes it releases methane
Evidence for natural climate change
ice cores - are cylinder samples extracted from ice sheets and glaciers. These cores contain layers of ice that have gathered over thousands of years of years each layer representing a year or season
Tree rings - when a tree trunk has been cut each ring represents one year of growth and the thickness of the ring reflects the environmental conditions that year. (wider rings =warm wet and narrow rings = cold dry)
Historical sources - offer qualitative data on past climate conditions eg. written records, paintings, archeological findings
Evidence for human climate change
Thermometer readings
Glacier retreats - photographs of glaciers taken years apart show that many of the worlds glaciers are melting and retreating
Ice cores
Rising sea levels
Predictions for global sea level
rise by 2100 vary from 20 cm to over 100cm
Predictions for average global temp
increase by 1• to 5•
Why are we uncertain about rises from human and natural contributions?
we can’t certainly predict future global temperature because earths climate system may respond to increased emmisions in the future
Human factors contributing to uncertainty
the future global population is uncertain
emmisions per person are tied to wealth and predicting future wealth is hard
uncertainty about wether humans will change their emissions or if they will continue to pollute
Natural factors contributing to uncertainty
the ice sheets in greenland and antarctica could melt faster in the future significantly raising global sea levels
the oceans capacity to absorb co2 might reach a limit
a warmer earth may lead to increased cloud cover, these clouds could reflect more solar radiation back into space, offseting some warming
What is a tropical storm?
is a powerful, low pressure weather system that forms in tropical regions. air rises rapidly causing low pressure on earths surface
Where do tropical storms form and why?
form over warm ocean waters (26-27•) where there is enough moisture and heat to fuel a storm
Often form between 5• and 20• north or south of the equator where the Coriolis force is stronger which helps the storm spin
Stages of a tropical storm
coriolis force helps the storm spin upwards around a calm central eye of the storm
moist air evaporates and rises creating low pressure. as it cools condensation occurs, creating clouds and conventional rainfall. Heat is given off when the air cools and powers the storm
cool air sinks into the eye. therefore there is no cloud so it is drier, clear and much calmer
storm travels across the ocean by prevailing wind( wind that blows in one direction)
Hits land and..
What happens when a tropical storm meets land?
it is no longer fuelled by the source of moisture and heat from the ocean so it looses power and weakens
LIC emerging/developing - Typhoon haiyan
The philippines
novemebr 2013
a category 5 tropical storm
wind speeds up to 195 mph
causes - warm ocean( in the western pacific
Primary effects of typhoon haiyan
90% of tacloban destroyed
6190 dead, highly due to storm surges
29000 people injured
4 mil made homeless
14 mil affected
electric was disrupted
airport badly damaged
1/3 of farmers and fishers lost their income ( fishers due to oil spill in the sea)
Secondary effects of typhoon haiyan
infection and disease spread mainly due to contaminated water
survivors fought for food supplies and 8 people died in the stampede
looting was high
power supply cut off for months in some areas
education was disrupted as many school destroyed
flooding caused landslides contributing to homelessness
Immediate responses to typhoon haiyan
government issued a televised warning to prepare and evacuate
800,000 were evacuated due to this, many found refuge in a stadium in tacloban however many died when it was flooded
a curfew was introduced 2 days after the typhoon to reduce looting
over 1200 evacuation centres set up to help the homeless
1 million food packs and 250000L of water distributed within 2 weeks
Long term responses to typhoon haiyan
a cash for work program paid people to clear debris and rebuild tacloban
oxfam replaced fishing boats
build back better was the government’s response. it tended to upgrade damaged buildings to protect them from future disasters
Why are some counties more vulnerable to tropical cyclones/ storms?
countries located in tropical and subtropical regions are more at risk as they are near warm oceans which is where a cyclone forms (nations near the caribbean)
mountainous regions can suffer landslides when rain fall is very heavy during a cyclone
places (emerging) that rely on agriculture face economic losses when crops are destroyed, food and jobs lost
areas with poorly constructed buildings and housing are more likely to be damaged
the capacity of healthcare and emergency services to respond to disasters
highly populated coastal cities are at greater risk as more people are vulnerable
HIC - developed - Hurricane katrina
america- neworleans
august 2005
category 5 hurricane
wind speeds up to 175mph
Primary effects of hurricane katrina
storms caused oil spills
1836 dead
more than 150,000 homes destroyed
electrical supplies for 3 mil ppl cut off
80% of new orleans flooded (levees were unable to cope with storm surge)
bridges and infrastructure collapsed
1200 drowned in flood
large tree loss
1 million made homeless
Secondary effects of hurricane katrina
looting occurred and tensions high as people felt unsafe
most of the transport and communication networks were damaged or disabled in new orleans due to flooding
Immediate responses to hurricane katrina
1.7 mil evacuated before it struck
charities provided food water and aid
more than 35000 ppl rescued by coastguard in neworleans
louisiana’s national guard asked for 700 buses to evacuate people however only 100 were sent
Long term responses to hurricane katrina
the government allocated 62billion to be spent in aid for victims
us government spent 20 mill rebuilding new ireland flood defence systems
