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Weather and Climate (Global Atmospheric Circulation (Different areas of…
Weather and Climate
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Natural Climate Change
Milankovitch Cycles
Long-term changes to the Earth's orbit and position, affecting the amount of solar radiation the Earth receives, affecting climate.
Eccentricity cycle: the Earth's orbit changes approximately every 100,000 years. Circular orbit = cooler periods; elliptical orbit = warmer
Precession cycle: the Earth "wobbles" on its axis every 24,000 years, changing the direction the axis is facing. This affects the differences between seasons
Axial tilt cycle: every 40,000 years the tilt of the Earth's axis varies. Greater angle = more extreme conditions (hotter summer cooler winter)
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Solar radiation levels just naturally vary. Lower radiation increase chance of glacial period, higher radiation causes inter-glacial period
Volcanic eruptions eject ash and dust into the atmosphere, acting like a blanket and blocking out solar radiation causing temperatures to fall
The Quaternary period (the last 2.6m years), where there have been more than 60 cold periods with ice advances lasting around 100,000 years and warmer inter-glacial periods lasting about 15,000 years
Recently, (in the last 250 years), the Earth's temperature has risen significantly compared to before, by about 5°C compared to the last ice age
Human activity
One of the main causes of global warming is greenhouse gases. Most of the heat energy from this the sun is radiated back to the space, but greenhouse gases like CO2 trap some of the heat
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Negative impacts
Melting ice sheets causes sea levels to rise. Arctic melting could cause the Gulf Stream to move further south and make Western Europe colder
Rising sea levels can cause coastal flooding. Soils will become contaminated with salt, causing plants to die.
Climate change near the Equator (like Sahel in Africa) could mean less rainfall and lower crop yields
Pacific islands like the Maldives can get flooded if sea levels rise, and these islands might have to be evacuated
The UK's climate
Past Climate Changes
Medieval Warm Period (950-1100): increased solar radiation > higher temperatures > better crop yield and growing population
Little Ice Age (1600-1685): Increased volcanic activity > decreased solar radiation > temperatures low enough to freeze the Thames
NE: cold winters, cool summers
SE: cold winters, warm summers
NW: mild winters, cool summers
SW: mild winters, warm summers
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