GCSE Geography Edexcel B - Hazardous Earth

Atmospheric circulation

the large-scale movement of air around the earth due to differences in temperature and pressure.

properties of a composite volcano

- sticky, viscous lava

- steep sides

- more explosive eruptions due to higher gas content

- tend to form on convergent plate boundaries

- less frequent eruptions

properties of a shield volcano

- gently sloping sides

- runny lava

- less explosive due to lower gas content, gentle eruptions

- frequent eruptions

- often form at divergent plate boundaries

What is the Coriolis Effect?

the effect of the earth's rotation on wind movements

what causes tropical weather?

rising air from the two hadley cells meeting causes low pressure and lots of rainfall, temperatures are hot and rainfall is high

what is climate change?

long term changes in weather patterns in a region over a long period of time eg. precipitation patterns

what is weather?

Day-to-day conditions of Earth's atmosphere

thermohaline circulation

Movement of ocean water caused by density difference, in a cycle of cooling and sinking

what causes arid/dry conditions

sinking air from the hadley and ferrel cells meeting causes high pressure and prevents rainfall, rainfall is very low for all or most of the year and temperatures are hot or warm

explain the process of global atmospheric circulation

- the sun warms the earth at the equator, causes a low pressure belt, air rises the cools and condenses to form clouds

- at 30 degrees north and south of the equator the air cools and sinks to form a high pressure belt with minimal rainfall and dry conditions, surface winds then blow the air towards the poles or to the equator

- at 60 degrees north and south of the equator cold air blown from the poles meets warm air surface winds, the warm air rises forming a low pressure belt, cloudy with lots of rainfall, some returns back to the equator with the rest going to the poles

- at the north and south pole cool air sinks forming a high pressure belt, the high pressure belt will move back towards the earth's equator as a surface wind

how else is heat transferred around the earth

ocean currents - large scale movements of water that transfer heat energy from warmer to cooler regions to moderate colder temperatures away from the equator (north atlantic drift)

Natural causes of climate change

1) The earth's orbit changes a small amount once every 100 000 years. This is known as the Milankovitch cycle.
- The Earth's orbit is sometimes circular, and sometimes more of an ellipse (oval).
- The Earth's axis tilts. Sometimes it is more upright, and sometimes more on it's side.
- The Earth's axis wobbles.

This changes the amount of sunlight the Earth receives and can also affect where sunlight falls on the Earth's surface.

2) *Volcanic eruptions - very large ones release large clouds of ash and particles, these particles reflect the sun's radiation away from the earth cooling it down (volcanic winter)

3) Large asteroid collisions can cause cooling as materiel blocks out the sun, just like a volcanic eruption.

4) solar output variation - the sun's energy output changes in cycles, its's possible that a period of high output would increase the earth's temperature

how to investigate past climate change

*tree rings - trees produce one ring within their trunks every year, the thickness depends on the climate when the ring was formed, the thicker the ring was the higher the temperatures

*ice cores - ice sheets are made up of layers of ice that form each year, scientists drill into the sheets and extract cylindrical ice cores these contain trapped gases by analysing the gases they can tell what the temperatures were each year

* historical sources - such as diaries and paintings

Possible consequences of global warming

- Melting ice caps,
- Loss of habitat/extinction of species,
- Rising sea levels/flooding of coastal cities,
- Droughts/Loss of agriculture,
- Climate change/more severe weather

Evidence for climate change

- Artic sea ice covers 13% less of the sea each decade
- Sea levels have risen by 14cm during 20th century

Characteristics of tropical cyclones

1)LOW PRESSURE: very warm, moist air rises through the atmosphere, sucking more air behind it.
2)ROTATION: the Earth's spin (Coriolis force) helps the rising air to spiral and drags in strong winds (the coriolis force is much weaker at the equator)
3)STRUCTURE: tropical cyclones form a cylinder of rising, spiralling air surrounding an eye of descending, high pressure air. They are up to 640KM wide and 10KM high.

Where do tropical cyclones form?

- Water temperatures are warm-over 26.5C
- Low wind shear

- tropical areas

- low pressure areas

When do tropical cyclones dissipate?

- Reach land because they lose energy (the are powered by water)
- Move into areas of colder water
- Run into other weather systems where winds are blowing in different directions

How do tropical cyclones form?

when warm ocean waters, typically with temperatures above 27°C, evaporate, causing moist air to rise, creating low pressure at the surface which draws in more warm air, leading to a cycle of rising air, rapid cooling causing condensation and lots of moisture to build up, and cloud formation, all while the Earth's rotation (Coriolis effect) adds a spin to the system, creating the swirling pattern of a tropical cyclone;

The inner core

In the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C.

The outer core

The layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel.

The mantle

The thickest section of the Earth at approximately 2,900 kilometres. The upper part of the mantle is called the asthenosphere. It is made up of semi- molten rock called magma.

Oceanic crust

Earth's solid crust located under the ocean, denser and composed of basalt, younger

Continental crust

Found under land masses or continents. It is generally older than oceanic crust and is less often destroyed, less dense than oceanic composed of granite

Hotspots

places where the magma rises up through the crust ,as the crust moves over these fixed spots, volcanoes are created, eventually forming a chain of volcanoes.

Convergent plate boundary

Usually involves an oceanic plate and a continental plate. As plates push together, oceanic plate is subducted. This is because oceanic crust is more dense than continental crust. As it sinks, it melts and creates magma, creating a volcanic eruption OR
Pressure builds up against the friction releasing seismic waves and when the plates finally snap, energy is released as a violent earthquake.

Collision zones

A type of convergent. Two continental plates collide. Neither can sink and so the land buckles upwards to form fold mountains. Earthquakes can occur at collision boundaries and landslides are triggered. Volcanoes are very rare.

Divergent plate boundary

The plates move apart from one another. When this happens the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano. The movement of the plates over the mantle can cause earthquakes.

Conservative plate boundary

The plates move past each other or side by side, moving at different speeds. Friction occurs as plates try to move and become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it releases seismic waves and it sends out huge amounts of energy, causing an earthquake. The earthquakes at a conservative plate margin can be very destructive as they occur close to the Earth's surface. There are no volcanoes at a conservative plate boundary.

why is it hard to predict future climate change

emissions - we don’t know how emissions will change as there are different factors to take into account such as population increase and economic development as we don’t know if they will continue to go up at the same rate or not

complexity - there are lots of natural processes that we do not fully understand yet which makes it difficult to predict what will change as we don’t know how these natural factors could have an impact on the environment

management - we don’t know what attempts there will be to manage the amount of greenhouse gases int he atmosphere or how successful they’ll be eg. will things like COP26 still take place