Physical Geography- Weather and Climate

  • Created by: Hologram
  • Created on: 03-04-18 13:37
what is weather?
refers to the state of the atmosphere around a certain local area, usually on a short term time scale. It emphaises aspects such as sunshine, cloud, rainfall, humidity and temperature
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what is climate?
is concerned with the long term behavior of the atmosphere. Climate is represented by data arranged over longer periods of time- eg climate graphs of rainfall and temp
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where is there a poitive heat balance?
in the tropics
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where is there a negative heat balance?
in polar areas and at a high altitude
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which sphere are 80% of the atmosphere's gases located?
troposhere
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what are the 5 layers of earth's atmosphere?
troposphere, stratosphere, mesosphere, thermosphere and exosphere (from lowest to highest
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what is the 'natural greenhouse effect'?
a natural process that warms the earth's surface. When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest of it is absorbed and re-radiated by greenhouse gases
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what are some examples of greenhouse gases?
water vapour, CO2, methane and nitrous oxide
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what is the rate of temperature change with increasing height in the troposphere?
approx 6.4 degrees Celsius every 1,000m- known as the Environmental Lapse Rate
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does air pressure and oxygen decrease or increase with height in the troposhpere?
decrease
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what are jet streams?
ribbons of very strong winds which move weather systems around the globe. They are found at the top of the troposphere (9-16 km above the surface) reaching speeds of 200 mph
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what is insolation?
short wave solar energy emitted by the sun
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roughly how much insolation reaches earth's surface?
50%
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roughly how much insolation is absorbed by earth's surface
68% (other 32% is reflected back to space)
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what is albedo?
reflective index of clouds and earth's surface
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what are some of the global factors affecting insolation?
height above sea level, altitude of the sun, land and sea and prevailing winds
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what are the three ways which heat is transferred vertically?
convection, radiation and conduction
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what are the two ways which heat is transferred horizontally?
winds including jet streams, hurricanes and depressions are responsible for 70% of heat transfer and ocean currents for 30%
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what are some examples of major ocean currents?
Gulf stream, N.Atlantic drift, West wind drift and N. Equatorial current
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in which direction do warm ocean currents flow?
ones that flow away from the Equatorial region are warm
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in which direction do cold ocean currents flow?
ones that move towards the Equatorial region are cold
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what are some of the factors that affect the speed and direction of wind?
pressure gradient, the Coriolis effect, gravity and friction
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what percentage of the global heat budget do ocean currents account for?
25%
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what is the 'thermohaline conveyor'?
this refers to the process where warmer less salty water travels north/south, becomes cooler and more slat laden as water evaporates, sinks and then returns to the equator balancing out the earth's heat budget
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what are some of the factors that influence the flow of the jet stream?
the continents, oceans, the Coriolis effect, solar energy and the seasonal angle of the earth
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what are some of the factors that can change the balance between incoming and outgoing radiation?
desertification, melting ice caps, pollution in the atmosphere, volcanoes, greenhouse gases and deforestation
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what is barometric pressure?
pressure exerted by the weight of air in the atmosphere of Earth
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how is wind generated?
by air moving from high pressure to low pressure along the pressure gradient
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what is wind speed measured by?
an anemometer
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what are global winds controlled by?
the global heat budget and the Coriolis force
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what is the Inter-Tropical Convergence Zone (ITCZ)
the meeting place of the trade winds from both the northern and the southern hemisphere (the Doldrums)
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what are the three different air masses made up in the Tricellular model?
the Hadley cell, Ferrel Cell and the Polar cell
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what are some of the criticisms of the tri-cellular model?
the model fails to take account of events, such as the El Nino, the distribution of continents, mountains or the complex movement of jet streams and the apparent overhead movement of the sun to the north and south of the equator
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In which direction do winds flow around a high pressure area in the Northern hemisphere?
clockwise
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In which direction do winds flow around a high pressure area in the Southern hemisphere?
anti clockwise
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what are the two jet stream waves that significantly influence our weather?
The boundary between the polar and mid latitude air (the Polar front) and the boundary between the mid latitude air and tropical air (the Subtropical Front)
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what are the factors that influence the flow of the jet stream?
the continents, the oceans, the Coriolis effect, solar energy and the seasonal angle of the earth
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what is a Rossby wave?
jet streams which meander north and south
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what can a Rossby wave cause?
can lead to a string of alternating high and low pressure systems, with the jet stream snaking around them from west to east
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If the conditions are right, can a Rossby wave remain stationary?
Yes, an example of this was in the summer of 2007 when the UK had widespread flooding while the Mediterranean and Eastern Europe experienced heatwaves and droughts
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When a Rossby wave remains stationary, what is the process known as?
Blocking
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what are jet streams?
strong upper air currents circumnavigating the globe
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what are the 'westerlies'
prevailing winds from the west towards the east in the middle latitudes between 30 and 60 degrees latitude
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where do the horse latitudes originate from?
originate from the high pressure areas in the horse latitudes and tend towards the poles
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what are the horse latitudes?
a belt of calm air and sea occurring in both the northern and southern hemispheres between the trade winds and the westerlies
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when are the westerlies strongest?
strongest in the southern hemisphere and and at times when the pressure is lower over the poles
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when are the westerlies weakest?
weakest in northern hemisphere and when pressures are highest over the poles
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what are the 'Roaring Fourties'?
the strongest westerly winds in the middle latitudes can come in the 'roaring fourties', between 40 and 50 degrees of latitude
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how do the westerlies play an important role in southern hemisphere?
they carry the warm, equatorial waters and winds to the western coasts of continents, especially in the southern hemisphere because of its vast oceanic expense
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what are some of the factors that influence temperature?
latitude, altitude, continentality, seasonality and types of land surafce
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how does latitude influence temperature?
the closer to the equator the higher the temperature, this is because at the equator, the vertical rays hit the surface at a more direct angle of incidence
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how does altitude influence temperature?
at higher altitudes, the amount of atmosphere decreases and as a result there is less water vapour in the air. The atmosphere absorbs less heat therefore the temp drops
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how does continentality influence temperature?
as land heats up rapidly, inland locations tend to have hotter summers than areas near the coast on a similar latitude. For areas near the coast when the sea is cooler than the land in summer, it lowers the temp of a coastal place and vice versa
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how does seasonality influence temperature?
seasons cause temperatures to increase or decrease ie summer causes it to increase winter to decrease
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how does types of land surface influence temperature?
dense forest would prevent solar radiation from reaching the ground directly so the ground remains cool whereas in the city the presence of concrete surface tends to keep air temps high
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how would you describe the Polar Maritime (PM) air mass?
a common air mass, cool conditions at any time of year, heavy showers and stormy
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how would you describe the Tropical Maritime (TM) air mass?
a common air mass in the British Isles, very mild and wet in winter with thick cloud, mild to warm in summer
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how would you describe the Polar Continental (PC) air mass?
very cold dry air in winter and may bring snow to the east which can last for several days, in summer it brings warm air
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how would you describe the Tropical Continental (TC) air mass??
hold and dry and normally occurs in summer, is relatively rare
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what 3 ways can air be cooled in order to form rain?
rising over mountains, rising over cooler air and rising due to thermal air currents
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what is relative humidity (RH)?
% of the moisture that air can contain at a given temp
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what is 'dew point'?
the point where water vapour turns into a liquid and clouds form- leading to precipitation (occurs at 100% RH)
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what are the 3 types of rainfall?
orographic/relief, cyclonic(frontal) and convection
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what is orographic/relief rainfall?
produced when moist air is lifted as it moves over a mountain range and produces high rainfall totals
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what is cyclonic rainfall?
caused by cyclonic activity and it occurs along the fronts of the cyclone. It is formed when two masses of air of different temperature, humidity and density meets
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what is convection rainfall?
When the land warms up, it heats the air above it. This causes the air to expand and rise. As the air rises it cools and condenses. If this process continues then rain will fall
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what are some of the features of a depression/frontal system?
low pressure, air moves anti-clockwise, it has many isobars, it has weather fronts (warm, cold and occluded), it iswindy, it is wet and weather is unsettled
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what is depresion/low pressure system?
a huge mass of spiraling air up to 2,500km across, which involves two contrasting air masses
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what two bodies of air do depressions have?
a body or sector of warm air, from the tropical region of the Atlantic, being gradually surrounded and lifted off the ground by cold polar air
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what is the contact zone between the warm and cold air caled?
a front
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how is a front classified as being a warm or cold front?
a front is described as being warm if, when it passes you enter warmer air. If it passes and you enter colder air its a cold front
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how are depressions shown on synoptic charts (weather maps)?
shown by a set of closed circular isobars, which are tightly spaced, indicating a steep pressure gradient giving powerful winds
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where do depressions usually come from in Europe?
regularly pass from west to east, arriving first on the wild Atlantic west coast of Ireland before crossing the islands on into the North sea and continental Europe
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how is a warm front indicated on a synoptic chart?
a line with semi-circles
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how is a cold front indicated on a synoptic chart?
a line with sharp triangles
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how is an occluded front indicated on a synoptic chart?
a line with both semicircles and sharp triangles
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what are some of he features of anticyclones/ high pressure systems?
dominated by stable conditions, air is descending forming an area of higher pressure at the surface, cloud formation is inhibited, winds are often quite light and in N.hemisphere winds blow in a clockwise direction around an anticyclone
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what is a 'blocking high'?
a large anticyclone that is well established over the country- this deflects depressions to the north and south
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what do anticyclones in winter often lead to?
forst and fog
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why do anticyclones in winter often lead to frost and fog?
the clear skies allow heat to be lost from the surface of the earth by radiation and light winds along with these falling temps encourage fog and frost to form
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what do anticyclones in summer often bring?
long sunny days and warm temps, dry weather and occasionally very hot weather can trigger thunderstorms
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what is a hurricane?
a large low pressure system characterised by high winds and heavy rain
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what are the main ingredients needed for a tropical cyclone to form?
hot, humid conditions over tropical areas
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where do cyclones get their energy from?
warm water which must be at least 27 degrees Celsius with a depth of 60m
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what is the difference between a hurricane, cyclone and a typhoon?
there is no difference, they are just given different names in different parts of the world
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how big can hurricanes get?
800km wide, the eye rarely exceeds 300km however
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what happens when a huricane hits land?
they lose their source of energy and their strength very quickly dissipates
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are hurricanes unpredictable?
yes
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can hurricanes be tracked?
yes
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hopw are hurricanes usually measured?
they are measured by using the Saffir-Simpson Scale of 1-5 depending on their windspeed and storm surge
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what are some of the factors the affect the amount of damage caused by hurricanes?
whether it is a populated or non-populated area, the development of the country, the warning given to residents and the preparedness of residents, whether the ground is saturated or not and if it is high tide or low tide
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what are the primary hazards of hurricanes?
wind and rain (often up to 500mm in 24 hours)
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what are the secondary hazards of hurricanes?
landslides, flooding and storm surges
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what is an example of a typhoon that caused a lot of damage?
Super Typhoon Haiyan
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what country did this typhoon affect the most?
the Philippines
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when did it strike the Philippines?
on November 7th and 8th in 2013
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where are the Philippines located
the Philippines are an archipelago of 7,000 islands located in the South China sea
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where does Haiyan unofficially rank in the most intense tropical cyclones ever observed?
4th
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what are some of the reasons as to why Haiyan occured?
global warming has increased sea levels by about 20cm since 1900, prevailing winds pushed cyclone towards Asia and sea temps over 27 degrees Celsius create warm and wet air which rises creating a low pressure zone near the surface of the water
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Is Haiyan the strongest typhoon to make landfall ever recorded?
yes- with windspeeds of up to 195mph and the accompanying storm surge sent a wave up to 5m high smashing through coastal communities
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what were some of the social impacts of Haiyan?
killed between 6,000 and 8,000 people, affected 9 million people, disease spread rapidly due to lack of food water and sanitation and i Talcoban 90% of the structures were either destroyed or damaged
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what were some of the economic impacts of Haiyan?
estimated cost $2.9 billion mainly due to damaged/destroyed infrastructure and lost production, major rice and sugar producing areas were destroyed, coconut plantations were "completely flattened" and 71,000ha of farmland were affected
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what were some of the environmental impacts of Haiyan?
loss of forests, trees and widespread flooding. Oil and sewerage leaks into the ecosystem. Lack of sanitation in days following the event also leads to a higher level of pollution
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what were some of the political impacts of Haiyan?
President Aquino was under pressure to speed up the distribution of food,water and medicine and the Talcoban city gov ceased functioning as any were killed, injured or too traumatised to work
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what was the population of the Philippines when Haiyan struck?
101 million people
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`what were some of the ways that you can prepare for hurricanes like Haiyan?
track hurricanes so they don't surprise you, have emergency drills in place and ensure that the population knows them, educate communities about the risk of heavy rainfall, strong winds and storm surges and plan evacuations
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what were some of the short term responses after Haiyan struck?
within 3 weeks an estimated 3 million had received food assistance, more than 35,000 households had received tarpaulin sheets or tents , about 80% of people in Talcoban city had received access to clean water and 60,000 hygiene kits has been given
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what were some of the medium term responses after Haiyan struck?
nearly 3 million are still relying on food assistance, lack of affordable shelter and construction materials delay their return home and vital to ensure a productive rice harvest in March and April 2014
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what were some of the long term responses after Haiyan struck?
rebuilding safer communites, break the cycle of disaster and poverty, improved warning systems and more accurate predictions of the path of the typhoon and better preparation for the next typhoons that will occur
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what does "El Niño" mean?
"the Christ Child"- because it often arrived around Christmas
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what happens in an El Niño event?
pressure and precipitation tends to reverse in the equatorial Pacific; and winds/atmospheric circulation and ocean currents either fail or reverse
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how long does El Niño usually last?
9 to 12 months
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how often does El Niño occur?
every 2 to 7 years
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what are the normal conditions (when it isn't El Niño)?
the tropical trade winds in the Pacific causes warm water to build up ob the western side of the ocean (near Asia), on the eastern side near Latin America, cold waters are pushed up towards the surface and wet conditions in the west and dry in east
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what are the El Niño conditions?
trade winds are weakened causing less warm surface water to be pushed to the west and less cold water to be pulled to the surface in the east, with the ocean temp evened out- rainfall patterns change and it becomes wet in the east and dry in the west
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what are some of the effects that El Niño has worldwide?
causes a decrease in rice production in Asian countries, droughts in Australia, flooding in Latin America, fishing in countries like Peru and Ecuador become difficult as water temps change and extremely cold winter in central North America
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what does ENSO stand for?
El Niño- Southern Oscillation
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what is the 'warm phase' of ENSO called?
El Niño
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what is the 'cool phase' of ENSO called?
La Nina
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what is the Coriolis force?
the invisible force that appears to deflect the wind
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which way does the wind appear to bend to in the Northern Hemisphere?
the right
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which way does the wind appear to bend to in the Southern Hemisphere?
the left
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which way do storms swirl in the Southern hemisphere?
clockwise
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which way do storms swirl in the Northern hemisphere?
anti-clockwise
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what are the two main air masses?
polar maritime and subtropical maritime
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what type of pressure does a Rossby wave cause when it meanders south?
low pressure
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what type of pressure does a Rossby wave cause when it meanders north?
high pressure
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what is climate?

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is concerned with the long term behavior of the atmosphere. Climate is represented by data arranged over longer periods of time- eg climate graphs of rainfall and temp

Card 3

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where is there a poitive heat balance?

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Card 4

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where is there a negative heat balance?

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Card 5

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which sphere are 80% of the atmosphere's gases located?

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