Topic 1: Hazardous Earth
Evidence for Climate Change
Recent
Distant
Dendrochronology
Soil samples show pollen grains from plants to when the UK was warmer
Tree rings are wider in warmer temperature and narrower in colder temperatures
Old records such as sketches and paintings
Glacial landforms such as U-Shaped valleys
Ice cores from glaciers in Iceland and Greenland show the concentration of gases in the air at that time
Definitions
Weather
Climate
Climate Change
Interglacial
Glacial
Cooling period
Warming period
Long term changes in the atmosphere, such as 30 years time period
How the average climatic conditions change over time
Short term, day to day changes in the atmosphere
Climate change theories
Eruption theory
Tropical Cyclones
Formation
Ciruculation of Heat
Atomspheric Circulation
Oceanic Circulation
Low pressure (below 1000mb) is formed by warm air rising. (Exerts less pressure on the ground). Air rises, condenses forming cloud and rain.
High Pressure (above 1000mb) is formed by cool air sinking. (Exerts more pressure on the ground). As it sinks, it warms up and any water evaporates. Clear skies and dry weather
The wind blows from areas of high pressure to areas of low pressure
Circulation Cells
Hadley Cell
Ferrel Cell
Polar Cell
Nearest to the poles
High pressure
Between Hadley and Polar
Nearest to the equator
Low pressure
Trade winds of low to high pressure from the equator to 30 degrees north/south to where it sinks
Global ocean currents play a large role in distributing heat from the equator to the poles.
Circulation is driven by cold water freezing into ice at the poles. This creates denser, saltier seawater which sinks to the ocean floor, the water that flows behind it at the surface forms a current
Short term climate change
Large volcanic eruptions emit vast amounts of ash into stratosphere causing global dimming
Mount Pinatubo, 1991, caused a 0.5 degree drop for a year
Asteroid collisons
Short term climate change
Impact blasts dush and ash into the atmosphere, similar to volcano but on a larger scale
Lasts for 5-15 years
Sunspot theory
Medium term climate change
Sunspots are dark patches on the surface of the sun which indicate that the sun is more active. More spots, more solar radiation, the warmer Earth is. Works vice versa too
E.g the medieval warm period and the little ice age. Causes change over a few hundred years
Orbital Theory
Eccentricity
Axial tilt
Precession
Every 26,000 years
Every 100,000 years (Milankoviwtch cycles)
Every 41,000 years
Orbit around the sun goes from circular to eliptical
Circular = Interglacial
Eliptical = Glacial
The Earth's axis tilts or straightens
Tilted closer to the sun, the differences between summer and winter are decreased
Earth's axis wobbles like a spinning top
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Form over warm tropical oceans with a surface temperature of above 26.5 degrees celsius
Warm, moist air rises through convection creating an area of low pressure. This sucks in more air from the surroundings
Warm air rises and condenses forming cumulonimbus clouds
Storm begins to rotate due to Coriolis Effect. Anticlockwise in the Northern Hemisphere and clockwise in the southern hemisphere.
The air flowing away cools and sinks back to the ocean, where the warm ocean water heats the air again causing a cycle.
Air that sinks within the eye wall results in localised high pressure. Here conditions are calm and the skies are cloudless.