GCSE Geography

2016/17Climate and climate change.

Basics

Weather versus Climate Weather is the state of the earth’s atmosphere at a given 🌍time, which changes daily.

Climate is what the weather is usually like, with measurements taken over long periods

Climatologists are scientists who specialise in climate and climate change

Sorry, but we've more terms to learnWe’ll be referring to them a lot!

The atmosphere is the layer of gases above the earth's surface. In the upper atmosphere, you'll find jet streams- fast moving currents of air. The Coriolis Effect is the deflection of air movement by the earth's rotation, which generates Coriolis force.

Precipitation is the descent of rain , sleet, hail or snow . ☔ ❄

Areas with little or no regular precipitation are described as “Arid”. The stratosphere, 10-50 kilometres up, is a layer of the atmosphere above the cloudy layer we live in.

Under pressure!Low air pressure is where warm air rises. In other words, the surface is cooler than the air above it.

High air pressure is where cool air descends. Put differently, the surface is warmer than the air above.

Trade winds carry moisture, travelling from areas of high pressure to those of low pressure.

“#Betterthanhistory”- Miss Trainor

Circulation cells Storms & weather in general is largely affected by the following few phenomena…

Polar cells bring cooler air south towards the UK. These cells are farthest from the equator.

Ferrel cells bring warmer air north towards the UK. These cells are found between a polar and a hadley cell.

Hadley cells, found either side of the equator, are responsible for tropical storms at the equator and desert belts north and south of the equator.

Between two hadley cells, we find the ITCZ, an area of low pressure which brings moisture.

Oceans too play a big partLand heats up quickly, as only the thin top layer is warmed, yet this also makes it lose its heat rapidly when the summer is over, as the heat fails to permeate much depth.

Ocean takes a long time to heat up, as the heat reaches many meters down. Yet, this means that it also loses its heat more slowly, giving off warmth long after the summer heat ends.

You might think all this would just stay the same……...but you'd be wrong!

Climate change Natural. We're gonna look at:

Orbital theory

Eruption theory

Asteroid collisions

Sunspot theory

Human activity. We're gonna look at:

The enhanced greenhouse effect, caused by industrial development, energy, transport & cattle farming.

Natural

Orbital theoryThis theory states that, over hundreds of millenia, the shape of the earth's orbit changes(this is known as eccentricity), which impacts our climate.

When the orbit is more circular, we're nearer to the sun, so the temperature is warmer. However, when the orbit is more elliptical, we're farther from the sun, so it's cooler on earth.

The cycles of the earth's changes in orbit shape are known as Milankovitch cycles.

Eruption theory Basically, massive volcanic eruptions churn out ash and sulphur dioxide gas, which block the sun's rays and thus make our climate cooler.

Cooler periods can be described as glacial and warmer ones as interglacial. Solar insolation is a measure of solar radiation received on a given surface area at a given time.

Asteroid collisions Every 500,000 years, massive asteroids strike the earth, which churn out clouds of dust and ash, acting like a blanket to block solar radiation. Therefore, earth will experience glacial periods.

Sunspot theory Dark spots on the sun indicate times when the sun is especially active/powerful, so the temperature will be higher when sunspots exist or exist in abundance.

Human activity

Four terms before we get into it...The greenhouse effect is where certain gases in the atmosphere act like the glass of a greenhouse, allowing heat in, but very little to escape.

The enhanced greenhouse effect is the same, but excessively because humans have produced too many greenhouse gases.

Greenhouse gases are gases which form a layer outside the atmosphere, keeping the earth warm. They are carbon dioxide, methane, nitrous oxide and halocarbons.

Global warming is a rise in average global temperatures.

89%Of greenhouse gases produced is CO2

Industrial development 🏭In recent years, people have seen an increase in disposable income. Hence, we demand more exciting things to spend it on.

Factories often churn out greenhouse gases.

250%Is how much methane release has increased since 1850

EnergyAs population and sophistication of technology increase, more energy is required . 💡 Fossil fuels (coal, oil and natural gas) are often burnt to generate steam to rapidly turn a turbine & convert kinetic to electric energy . ⚡These are non-renewable and pollute the environment, but they also contribute to global warming via the enhanced greenhouse effect.

3000xThat's how many times more powerful (and thus toxic)

halocarbons are than carbon dioxide

Transport With globalisation comes increased interconnectedness, and this of transport too. More flights, drives, ferries and train journeys happen now than ever before. Jet fuel increases in demand, meaning more nitrous oxide is released. So does car fuel , so more CO2 is released. 🚗 ⛽

Cattle farming The global population has increased in size, so meat and 🍖cattle products have seen an increase in consumption and so too in demand. More cattle farms and more cattle therein also mean more faeces. Cattle dung releases methane into the atmosphere.

How do we

know?

Here's how...Natural

Ice cores help us take atmospheric samples and use isotopes to reconstruct temperatures. Ice thickness also means cooler temperatures.

Historical sources like monk chronicles wrote about weather, though their measurements may be a bit off.

Tree rings are thicker when it's warmer.

Unnatural

Sea levels are higher due to thermal expansion due to global warming.

Arctic ice melts when it's warm. Nowadays, there's very little sea ice.

Just before this ends...When particles are heated, they become energised and thus ‘excited'. Hence, they move about quickly and so spread out. In oceans, this spreading of particles means that the water takes up more room. Therefore, the sea 🌊level rises. This is called thermal expansion.

That's all folks!

Thanks for watching & I hope this helps