weather hazards and climate change

what is global atmospheric circulation ?

the worldwide system of winds, which transports heat from tropical to polar latitude

what are the 3 cells ?

hadley, ferrell, polar

what is low pressure ?

air that is rising from the ground’s surface

is rising warm air more or less dense ?

less dense

what are the characteristics of low pressure ?

cools, condenses, clouds and rainfall (sometimes)

what is high pressure ?

air that is sinking

is sinking cold air more or less dense ?

more dense

what are the characteristics of high pressure ?

sunny, no clouds, no rain

explain the process of global atmospheric circulation

1. the earth receives heat from the sun in the form of solar radiation

2. as radiation passes through the atmosphere, the ground heats up and warm air rises

3. the equator receives more solar radiation than the poles, making it warmer there

4. warm air rises at the equator as it’s less dense, creating low pressure

5. as the air rises, it cools and moves away from the equator towards the poles

6. around 30° north and sound, the cooled air sinks as its denser, creating high pressure zones

7. the sinking air then moves back towards the equator along the surface, creating trade winds

8. the same process also happens in both the ferrel and polar cell, which together move heat energy around the world and create global wind patterns

what are the winds calls at 0 - 30° north ?

north east trade winds

what are the winds called at 0 - 30° south ?

south east trade winds

what are the winds called at 30 - 60° north and south ?

westolies

how do winds always move ?

from high pressure to low pressure

what is the coriolis effect ?

the coriolis effect is winds moved in a curved direction due to the earth’s rotation on its axis

how does the coriolis effect influence wind directions ?

northern hemisphere - curves winds to the right

southern hemisphere - curves winds to the left

what are deep ocean currents driven by ?

differences in water’s density, which is controlled by temperature (thermo) and salinity (haline)

what is thermohaline circulation ?

these deep ocean currents are driven by differences in the water’s density, which is controlled by temperature (thermo) and salinity (haline)

what does more salt equal to ?

more dense (cold water)

explain the movement of heat and water through the globe via the current

1. water gets heated at the equator

2. the warm air and wind moves the current to the poles

3. the water temperature decreases and density increases

4. the water sinks

5. water moves back to the equator and gets reheated

describe arid environments

located in areas of high pressure, receiving less than 250mm of rainfall for per year

what is the inter tropical convergence zone (ITCZ)

located between the two hadley cells as intense heating causes air to rise creating low pressure and experiences high rainfall

what is glacial ?

cold period of time

what is interglacial ?

warmer period of time between two glacial periods

what is climate change ?

how the average climate conditions of earth change over time

what is the planet’s history divided into ?

periods

the climate has changed many times during the what period ?

the quaternary period

when was the last major cold period ?

started 2.6 million years ago and ended 10,000 years ago

what was the last major cold period known as ?

the pleistocene

what is the current warm phase known as ?

the holocene

a new epoch of the anthropocene is said to have started when and what can we see ?

started in 1610

we can see that peopl had a significant influence of the earth

what are the 3 different types of the milankovitch cycles ?

eccentricity, axial tilt (obliquity), precession

explain eccentricity as a cause of climate change

• the earth’s orbit is elliptical (oval shaped), which causes the amount of solar radiation to vary throughout the year

• when the earth is closer dye it the ellipse, we get warmer periods, when it’s farther away, the earth is cooler

• cold periods happen when it’s more elliptical

explain axial tilt as a cause of climate change

• the earth’s axis changes

• the greater the tilt towards the sunk the warmer the temperature

• tilts further away = less solar radiation

• the angle of the tilt changes due to the gravitational pull of the moon

• the tilt changes every 41,000 years and moves between 24.5° and 22.5°

explain precession as a cause of climate change

the earth is not a perfect sphere so it wobbles on its axis, which impacts seasons and can cause warmer summers if it wobbles closer to the earth or milder summers if wobbles away

what are other natural causes of climate change ?

solar variation (solar radiation)

surface impact

volcanism

explain solar variation (solar radiation) as a cause of climate change

the output of the sun is measured by overseeing sh sports on the sun’s surface; the more flares / sun spots, the hotter the earth is. this causes more solar radiation to be absorbed into the atmosphere as sunspots give off radiation. very few sunspots were observed between 1645 and 1715, which coincided with very cold temperatures and bad winters in europe, it became known as the “little ice age” an active sun is called modern maximum and an inactive sun is called maude minimum

explain surface impact as a cause of climate change

large object from space (asteroids or comets) can impact the earth’s surface which can release huge volumes of dust into the atmosphere, partially blocking solar radiation and leading to glacial periods. it is thought that an asteroid impacting the climate was responsible for the extinction of the dinosaurs, nor the impact itself

explain volcanism as a cause of climate change

volcanic erosions send huge amounts of ash, gas (sulphur dioxide) and dust into the atmosphere. during big eruptions, if this debris gets into the stratosphere, it can have a cooling effect on the earth’s climate. this is because the volcanic material in the atmosphere causes the sun’s radiation to be reflected back into space. tambara was the most powerful eruption, dust and sulphuric acid caused global temperatures to drop by 0.4℃ - 0.7℃ and 1816 became known as the ‘year without summer’

what are the greenhouse gases ?

water vapour

carbon dioxide

methane

nitrous oxide

ozone

explain the process of enhanced greenhouse effect

1. solar radiation arrives as short wave radiation and passes through the greenhouse gas layer

2. most radiation is absorbed by the earth’s surface and warms it

3. some solar radiation is reflected by the earth and the atmosphere

4. waves reflect back as long wave radiation, but it cannot pass through the greenhouse gas layer and heat is trapped. this warms the atmosphere

5. some infrared radiation gets remitted from the earth’s surface

what is the difference between natural greenhouse effect and enhanced greenhouse effect ?

natural greenhouse effect: more heat escapes into space and less re-emitted heat

enhanced greenhouse effect: less heat escapes into space with more greenhouse gases trapped in the atmosphere and more re-emitted heat

why does the temperature or the atmosphere increase over time ?

as concentrations of these greenhouse gases build up due to human emission (e.g. burning fossil fuels), more heat is prevented from being lost into space

what are evidences of climate change

ice cores

pollen analysis

tree rings

glacial retreat

historical source

explain ice cores as an evidence for climate change

deeper ice means older ice. scientists will extract the cores and analyse the composition of gases to determine climate of a specific period going up to 1.6 million years ago. it can provide data up to 800,000 years ago. this is one of the most reliable methods due to being untampered with

key facts / examples of ice cores as an evidence for climate change

in colder climates, oxygen (o18) is taken up in greater proportion. low proportion of o18 = warm period and high proportion of o18 = cooler period

is ice cores reliable as an evidence of climate change ?

it is less accessible as it can only be collected from cold climates such as iceland or greenland

explain pollen analysis as an evidence of climate change

we can extract pollen to identify wheee and when the plants came from. if we extract pollen from 1000 years ago that came from tropical plant. we know the climate must have even warm at the time

key facts / examples of pollen analysis as an evidence for climate change

evidence shows that palm trees were in antarctica 52 million years ago

is pollen analysis reliable as an evidence of climate change ?

one of the best methods for reconstructing climate conditions over the past 15,000 years

explain tree rings as an evidence of climate change

each year, a tree grows a new ring, during warm conditions, the ring gets thicker.

wider rings for warmer period = summer

narrow rings for cooler climates = slow growth + winter

key facts / examples of tree rings as an evidence for climate change

the circumference of the rings only tell us about short term growth and period

are tree rings reliable as an evidence of climate change ?

cloud cover can slow tree growth making it less reliable

explain glacial retreat as an evidence of climate change

glacial retreat (melt) in warmer temperatures, this can be mapped

recent melting indicates warmer temperatures

key facts / examples of glacial retreat as an evidence for climate change

artic sea has thinned by 65% since 1975, and the total area of artic sea ice was at an all time low in 2024

the ‘mer de glade’ - a glacier in the alps near chamonix - has retreated by approximately 1300 metres in the past 200 - 250 years

is glacial retreat reliable as an evidence of climate change ?

only good for short term change

explain historical sources as an evidence of climate change

historical paintings, books, diaries, newspapers and thermometer endings give us evidence of what the climate use to be like

books, paintings (e.g. the “frost fair”) on the river thames and even cave paintings indicated we use to have more extreme temperatures here in the uk

charles didkens’ novels describes very cold winters (e.g. a christmas carol)

key facts / examples of historical sources as an evidence for climate change

we’ve used diaries all the way up to 1915

thermometer readings have even accurately used since 1851, showing an annual increase in temperature

are historical sources reliable as an evidence of climate change ?

due to it being a qualitative source, it is subjective

what are the 4 main human causes of climate change ?

industry, transport, energy, farming

explain how does industry add to the greenhouse effect

as high levels of disposable income rise increased demand for goods has arisen. this led to industrial growth and the need for more energy meaning more fossil fuel burned

explain how does transport add to the greenhouse effect

almost all types of transport rely on burning fossil fuels in some way. transport has developed hugely with flights becoming more common and cars becoming more affordable - meaning more fossil fuel burned

explain how does energy add to the greenhouse effect

the demand for electricity is growing because of increasing population and new technologies

explain how does farming add to the greenhouse effect

population growth has led to a hugged demand for food production. mechanisation on farms means more fuels used to produce this food

how do we add to the greenhouse effect ?

flying - CO₂ and N₂O

driving cars - CO₂ and N₂O

deforestation - CO₂

power station - CO₂

rice + cow farming - CH₄

burning fossil fuel

energy waste - CO₂

how has the earth’s average surface air temperature increased and by how much? 

increased by 1℃ over the last 100 years due to the greenhouse gases trapping heat

what did world leaders agree to at the climate conference in Paris ?

they agreed to limit the rise in global temperatures by 1.5℃ over the next century

how much has sea levels risen by since 1900 and will it continue ?

sea levels have risen by 19cm since 1900 and are expected to continue to rise due to thermal expansion and ice sheets melting

what temperatures are the warmest since 1850 ?

ocean temperatures are the warmest since 1850 

what does NASA data show since 2002 ?

the volume of ice loss on Antartica is 134 billion tonnes per year and 287 billion tonnes in Greenland ?

what are possible effects of climate change ?

• drought

• flooding

• forest fire / wild fire

• tornadoes

• hurricanes

• extinction

• habitats loss = loss of biodiversity

• average temperatures increasing

• crops dying = crop yield decreases

• pests + disease more widespread

• water supply problems caused by loss of glacial

• more frequent and heavier precipitation

what are some social impacts of climate change ?

• fishing would decline in areas like the Lower Mekong delta due to changing water temperatures (SE Asia), affecting 40 million people

• increased severe drought risk in Sub-Saharan African - leading to crop failure, famine and malnutrition / starvation

• more incidence of skin cancers and strokes related to the heat

• by 2020, about 75 to 250 million people are projected to be exposed to increased water shortages

• in Europe, more heat waves can increase deaths, but deaths related to colder weather may decrease

• decline in yield of thirsty crops such as rice, wheat and maize

• the chief benefits of global warming include: fewer winter deaths; lower energy costs 

• in SE Africa malaria may increase in hot humid regions that remain hotter for longer in the year

what are some economic impacts of climate change ?

• decline in yield of thirsty crops such as rice, wheat and maize

• sea level rise will affect low-lying countries - tourism dependent places like the Maldives may be under water

what are some environmental impacts of climate change ?

• coral reefs such as the Great Barrier Reef could see biodiversity lost, and warmer, more acidic water would cause coral bleaching

• forests may be affected by pests, diseases and forest fires more (e.g. 2023 Rhodes wildfires)

• warmer rivers across Asia could affect marine ecosystems - animals would struggle to adapt

• ice retreat could affect penguin species in Antartica and polar bear and seal populations in the Artic

• decline in yield of thirsty crops such as rice, wheat and maize

what are the 3 main factors the UK’s rainfall linked to ?

relief of the area - steeper = more rain

influence of the rain shadow - mountain blocks the clouds

temperature difference - warm + cold air creates rain

what are the 3 types of rainfall

relief rainfall

convectional rainfall

frontal rainfall

explain relief rainfall

relief rainfall occurs where moist air is forced to rise over mountains. as the air rises, it condenses and forms clouds which deposit precipitation as rain, hail or snow on the mountains. on the opposite side of the mountains it is drier

explain convectional rainfall

convectional rainfall happens when the ground is heated by the sun and the air just above it warm up. because it is warm that air rises and as it does it cools down and clouds form. in Britain this often causes heavy rainfall and thunderstorms on very hot days in the summer

explain frontal rainfall

frontal rainfall occurs when a mass of warm air meets a mass of cold air. the lighter warm rises over the heavier cold air and cools, so clouds form and rain fallows. the place where cold and warm air meet is called a frontal. frontal rainfall is very common in Britain, especially in winter

How has the climate changed?

1100 AD (interglacial period) - sea ice melts, vikings begin exploration up north

800 - 1400 AD (medieval warm period ) - vikings in greenland farmed green land traded overseas due to lack of sea ice

little ice age - coldest around 1700 AD, paintings show Frost Fairs as the River Thames froze over and Mt Tambora erupted in 1815 and crested the ‘year without summed’

modern era - anthropogenic climate warming, causes by modern human activities

define relief

steep

define gentle

flat

define weather

the day-to-day atmospheric conditions and variations in a region often measured over hours and days

define climate

long-term weather pattern in a region, typically averaged over 30 years

define air mass

a large volume of air with similar temperature and humidity characteristics, which travels from one area to another

what is the weather that air mass bring determined by

the weather that air mass brings is determined by the region wheee the air has come from

what is polar air mass

cold

what is tropical air mass

warm

what is maritime air mass

wet (sea)

what is continental air mass

dry (land)

explain polar maritime air mass

it is from greenland / artic sea and wet, cold air brings cold showery weather

explain artic maritime air mass

it is from artic and weak, cold air brings snow in winter

Explain polar continental air mass

It is from central europe and hot air brings dry summers whilst cold air brings snow in winter

Explain tropical continental air mass

It is from North Africa and hot, dry air brings not weather in summer

Explain tropical airtime air mass

It is from Atlantic and warm, moist air brings cloud, rain and mild weather

Explain returning polar maritime air mass

From Greenland/artic via North Atlantic and moist, mild and unstable air brings clouds and rain showers

Define prevailing winds

The dominant wind direction

What can the dominant wind direction affect?

The climate and it it is travelling from a cool or hot place, it will bring some of that with it

Where do the prevailing winds in the UK comes from?

South west

What happens when the prevailing wind travels over land?

It will be dry

What happens when prevailing wind travels over sea?

It will be wet