Hazards

Paper 1- World

what is wind

the movement of air on a large scale; made up of gases

what causes wind

differences in air pressure

what causes differences in air pressure

different temperatures; its hotter at the equator compared to the poles causing differences in pressure when the air moves up and down

what pressure do winds move from and to

from high pressure to low pressure

what are surface winds

they blow air that sinks either towards the equator or away from it at the surface of Earth

what are the two types of surface winds

• trade winds

• westerlies

what are trade winds

surface winds that blow from 30N+S back towards the equator

what direction do trade winds blow in the southern hemisphere

from SE to NW until they reach the equator

what direction do trade winds blow in the northern hemisphere

blow from NE to SW until they reach the equator

what happens when the trade winds meet at the equator

they are then heated again and the cycle begins

what are westerlies

surface winds that blow from 30N towards the north pole and 30S towards the south pole

what direction do the westerlies blow in the southern hemisphere

blow NW to SE until they reach the south pole

what direction do the westerlies blow in the northern hemisphere

blow SW to NE until they reach the north pole

what are latitude lines

encircle the Earth,, dividing it into north and south

where is most of the suns energy directed

at or near the equator

what is Earth’s main source of heat and how does it travel to us

main source is the sun and it travels through space via radiation

what is the main reason why some parts of Earth receive more of the suns radiation than others

main reason for this is the curvature of the Earths surface

what happens to the suns radiation at higher latitudes and why

it is spread over a much larger surface area due to the curvature of the Earth

why is it colder at the poles than the equator

• the curvature of the earth means that the same amount of the suns radiation is spread over a larger area

• this means that it is overall colder

• it is also very snowy here and snow reflects the suns energy, further making it colder

properties of places with low air pressure

• air rising

• rain

• wind

• hot

• humid

properties of places with high air pressure

• air is sinking

• clear skies

• no clouds

what does global atmospheric circulation do

redistributes the suns radiation to make sure that the Earths temperature is habitable; without it it would be way too cold at the poles and way too hot at the equator

what happens to air and heat at the equator

• at the equator, Earths surface warmed by the sun at equator

• earth transmits this heat to nearby air which gets hotter and rises

• rising hot air

• as hot air rises, air will begin to cool with water vapour condensing creating rain clouds

• rising air cools and moves away from the equator towards 30N+S

what pressure is present at the equator

low pressure belt from the rising hot air

what happens to air and temperature at 30N+S

• air is further from the equator and the cool air falls

• this results in minimal rainfall and no clouds

• when the cool air reaches the Earth's surface, surface winds blow the cool air either towards the equator or away from the equator towards the poles

what air pressure is at 30 N+S

high pressure belt

what happens to pressure and temperature of air at 60N+S

• cold air blown from the poles meets warm air surface winds

• warmer air less dense and rises to form a low pressure belt

• air splits, some returning back towards the equator and rest heading to the poles

what happens to air temperature and pressure at the poles

• cool air sinks

• belt of air moves back towards the Earth’s equator as surface winds

what air pressure is at the poles

high pressure

what are the three cells

• hadley

• ferrell

• polar

properties of the hadley cell: its size, where its located, air temperature, direction it flows in, where it escapes to

• largest cell and closest to the equator

• warm air

• anti-clockwise

• some escapes into the Ferrell cell where its temperature drops as its moving north

properties of the Ferrell cell: its size, where its located, air temperature, direction it flows in, where it escapes to

• second largest cell

• air has mild temperature

• clockwise

• some air escapes into the Hadley cell, so becomes warm and some blows north to polar cell becoming cold

properties of the Polar cell: its size, where its located, air temperature, direction it flows in, where it escapes to

• near the poles

• cold air

• anti-clockwise

• some air escapes into the Ferrell cell, so it gets warmer

how does atmospheric circulation distribute heat energy from the equator to the poles

• distributes energy through three different cells

• hadley close to equator and heated by he sun, causing hot air there to rise

• as it rises, air moves anticlockwise up to around 30N+S where it gets colder due to rising and so begins to fall creating high pressure area

• cold air then falls and is heated again when its close to the surface

• as it heats again, it rises and moves clockwise to the poles, in the Ferrell cell

• air is then carried to the poles and polar cells, moving anticlockwise

• means atmospheric circulation uses cells and the rise and fall of temperature to distribute energy

why do the highest temperatures generally occur near the equator

suns energy mainly focused on the equator, meaning theres much more energy heating the air near the equator, whereas the suns energy is less concentrated elsewhere so therefore the highest temperatures generally occur at the equator

why is it cloudy and wet in the UK

UK located at around 55N so is right in between hot air moving north from equator and cool air moving south from polar regions; here there is low pressure, meaning hot air is rising and forms clouds and lots of rain

why is it hot and dry in the desert

deserts found at around 30N+S where the Ferrell and Hadley cells meet

air pressure here high as hot air sinks

climate in areas of high pressure is hot and dry as the air isn’t rising so there aren’t many clouds

what is the role of ocean currents

to help redistribute warmth around the globe

how is heat from the tropics transferred to polar regions via ocean

largescale water movement within the oceans

examples of ocean currents

North Atlantic Drift in the Atlantic ocean

what causes ocean currents

the prevailing surface winds associated with the general atmospheric circulation

also the coriolis force

what are the two types of ocean currents

• surface currents

• deep ocean currents

what causes surface currents

winds

what is the role of surface currents

transfer heat from the equator to cooler regions

example of a surface current

warm water transferred to western Europe from the Caribbean by the Gulf Stream

what causes deep ocean currents

caused by differences in water density

what is thermohaline circulation

• water freezing in polar regions causes the surrounding water to become saltier and therefore denser

• the sinking of this dense water lets warm water flow near the surface which then cools and sinks continuing the cycle

explain how ocean currents can influence climate

• ocean currents transport warm water and precipitation from the equator towards the poles and cold water from poles back to tropics

• ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching the Earths surface

• without currents in ocean, regional temperatures would be more extreme; super hot at the equator and frigid towards the poles and much less Earth would be habitable

• Gulf stream an ocean current that carries warm water up the Easter coast of the USA and Canada onto western Europe

what is climate change

the long-term shifts in temperatures and weather patterns

global warming definition

long-term heating of Earths surface; a form of climate change

how many cycles of climate change are there

3

what period of climate change are we in at the moment

quaternary period

what happens within the quaternary period

• cycle between glacial and interglacial periods

what are glacial periods like and how long do they last

cold and last for 100,000 years

what are interglacial periods like and how long do they last

7 degrees warmer and last for 8000-12000 years

what methods can be used to evidence climate change

• ice cores

• tree rings

• historical evidence- painting/diary

• historical evidence- scientific records

how do ice cores evidence climate change

• layers of snowfall each year which trap air bubbles of CO2 from the time when they froze

• by measuring amount of CO2 trapped in this ice each year, scientists can predict temperatures at that time

• can be extracted by drilling into ice sheets

advantages of using ice cores as evidence of climate change

• scientific evidence

• reliable

• has proof to support this

how are tree rings used to show evidence of past climate change

• in temperate climates, trees grow every summer and these periods of growth can be seen from the number of rings a tree has

• give data on the climate and temperature for up to the last 10,000 years

what happens to tree rings during warmer and wetter years

the tree grows more and therefore has wider rings

what happens to tree rings in dry and cold years

less growth

advantages of using tree rings

• scientific evidence

• shows the exact year

disadvantages of tree rings

• not exact numbers; may know if its hotter or colder but not specific temperatures or rainfall

what do paintings/diaries show about temperature and weather in the past

they show what the temperature and weather looked like at a time in a particular area

advantages of historical evidence of paintings and diaries for evidence of climate change

• people actually there experiencing this weather

• record of recent climate trends

• very specific places weather

disadvantages of historical evidence of paintings and diaries for evidence of climate change

• may be exaggerated or biased

• not real photographs

• only very specific area

• not scientific; no exact numbers

• only from when humans were literate, not all evidence would have survived

how are historic scientific records used as evidence for climate change

show records of temperatures taken by humans at the time

how long have global temperatures been measured

since 1850

advantages of using scientific records as evidence for climate change

• record taken with scientific equipment

• can be taken locally and on a wide scale

disadvantages of using scientific records as evidence for climate change

• records got a lot better from the last 50 years; before this maybe more inaccurate

• didn’t have good enough equipment

• only stretches back 170 years; only recent history

• may be biased

• often very localised

two examples of largescale weather changes in the UK in history

• medieval warm period

• little ice age

when was the medieval warm period

950-1000CE

what was the climate like in the medieval warm period

1 or 2 degrees warmer than in 2000; warmer summers and milder winters

why did the medieval warm period occurr

due to a combination of increased solar radiation and decreased volcanic activity

when was the little ice age

1350-1850CE

what is an ice age

a period of long term reduction in the temperature of the Earth’s surface and atmosphere

what happens to the world when there is an ice age

colder; expansion of continental ice sheets, polar ice sheets and alpine glaciers

impacts of the little ice age

• difficult farming conditions; frost damages cros

• shorter growing season

• snow cover made harvesting crops difficult

• frozen ground preventing ploughing

• food shortages lead to famine

• increases in deaths due to illness and malnutrition

• migration to warmer regions; animals and humans

• transport affected; frozen rivers, impassable highlands etc

• introduction of new crops to suit colder climates

• extended periods of cooler summers and winters

impacts of the little ice age on the ecosystem

• increased ice in northern hemisphere

• some animals facing rapid population decline

• slow plant growth

what are the natural causes of climate change

• changes in solar output

• variations in Earth’s orbit

• volcanic activity

• asteroid collisions

does changes in solar output make the Earth hotter or colder

hotter

how does changes in solar output make the Earth hotter

• solar energy (sunspots) works in cycles so that the suns energy varies over short periods on approx 11 year cycles

• leads to warmer climate

what are milankovitch cycles

the Earths orbit varies every 100,000 years with changes in the Earths axis every 41,000 years

how do variations in the Earths orbit cause climate change

• these cycles change how close the Earth is to the sun and therefore impacts climate

• thought to be the main factors that affect glaciation cycles

• can make the Earth hotter or colder depending if Earths orbit getting closer or further

how does the temperature change if Earth is closer to the sun

more radiation so hotter

how does temperature change if Earth is further from the sun

less radiation so colder

how many glacial-interglacial cycles have occurred in the past 800,000 years

8

how does volcanic activity cause climate change

• eruptioons release large quantities of volcanic dust which reflecs the suns radiatio away

• increasees cloud cover and rainfall for 1-2 years after the event

• suns radiation cannot enter atmosphere and Earth cools

• also releases CO2

how long do volcanic winters last

around 1-2 years

does volcanic eruption make the Earth hotter or colder

colder

how do asteroid collisions cause climate change

• when asteroids collide with Earth, huge amounts of dust particles get thrown up into the atmosphere

• this dust and ash goes into the atmosphere, reflecting the suns radiation away from Earth, causing the planet to cool

does an asteroid collision make Earth hotter or cooler

cooler

how long do the impacts of an asteroid last for

5-10 years

what are the four greenhouse gases

• carbon dioxide (CO2)

• methane (CH4)

• nitrous oxide (N2O)

• water vapour

are greenhouses good and why

yes they are; they help keep our atmosphere at a hot enough temperature for us to live and without them the Earth would be -18 degrees and uninhabitable

what happens when greenhouse gases occur

• solar radiation passes through the clear atmosphere; most of it is absorbed by the Earths surface and wars it while some reflected by Earth and atmosphere back into space

• some of this radiation passes through the atmosphere and some is absorbed and re-emitted in all directions by greenhouse gases

• warms the Earths surface and lower atmosphere

what happens when there are too many greenhouse gases

global warming

what is global warming

a rise in temperatures which makes the Earth too hot

what is the name of having too much greenhouse gases

the enhanced greenhouse effect

what causes the enhanced greenhouse effect

humans producing too many greenhouse gases