Topic 1 Flashcards
How does the earth receive solar radiation
The Earth receives its radiation from the sun as radiation passes through the atmosphere and heats the ground, which heats the air above it and makes it less dense, making it rise
How is solar radiation distributed
At the equator, the sun’s rays are concentrated over a small area and strike at a right angle, so temperatures are greater.
At the poles, radiation has to pass through more atmosphere and the sun’s rays are concentrated over a larger surface area since they reach the surface at a lower angle.
What is air pressure
Pressure at the earth’s surface
How is there low pressure
Heated air rises, transferring heat to the atmosphere as it cools and condenses to form clouds and rains - less air at the surface/pressure on the ground
High pressure
Air falls as it cools due to less energy, warming the ground as it falls leaving clear skies, more air at the surface means there is high pressure on the ground, low rainfall
Atmospheric pressure
The weight of the air and the force it exerts on the ground
The Coriolis effect
Due to the Earth’s rotation and winds forming due to different areas heating and cooling(air moved from high to low pressure),
the wind is deflected to the right in the Northern Hemisphere and left in the Southern Hemisphere
Low pressure belts
The equator - The Earth is warmed causing the air above to
rise to create a low pressure belt,
air cools and condenses, Hadley Cell
60 degrees North and South of the Equator - Between the polar and ferrel cells,warm surface winds meet colder air from poles, warm air rises creating frontal rain(when warm and cold air masses meet)
High pressure belts
At 30 degrees north and south of the equator,cool air from the equator sinks(between Ferrel and Hadley cells)
At the poles, cool air sinks, air drawn back towards the equator as surface winds(polar cells). Air is returned back towards the surface of the Earth.
Surface winds
When cool air reaches the ground surface and moves either back to the equator or towards the poles
Trade winds
Surface winds blowing towards the equator, blow from SE in Southern Hemisphere and NE in Northern Hemisphere, at the equator these trade winds are heated by the sun
Westerlies
Surface winds blowing towards the poles, from NW in Southern Hemisphere and SW in Northern Hemisphere
What are ocean currents
Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions.
How do ocean currents form
When water freezes at the poles water becomes saltier increases the density, meaning it sinks and warmer water flows at the surface, creating a current
What is thermohaline circulation
The cycle of water cooling and sinking due to density moving water in a big loop around the Earth
Arid areas
Arid areas are mid-latitude areas(30 degrees North and South of the Equator) which receive low average rainfall(less than 250mm per year) due to high pressure. An example in Tindouf, Algeria
Why are areas arid
Intense solar radiation
Sinking dry air blows outwards to block moist winds
The Inter-tropical convergence zone
A permanent zone of low pressure which experiences the highest rainfall. This zone moves through the tropics taking heavy rainfall with it
Where is the ITCZ
Near the equator between two Hadley cells
Why is there heavy rainfall in the ITCZ
Rising air causes cumulonimbus clouds to form.
How does the Earth’s tilt affect the Sun?
In June the Sun is directly overhead at 23.5 degrees north(Tropic of Cancer) and in
December at 23.5 degrees south(Tropic of Capricorn)
What is natural climate change
Refers to how the average climatic conditions of the planet vary over time during the Quaternary period(last 2.6 million years)- climate has been warming since the last glacial period 15000 years ago
How long do glacial periods last
100,000 years
How long do interglacial periods last
10,000 years
How do orbital changes explain why the climate has changed in the past
The Milankovitch cycles change the Earth’s orbit which affects how much radiation we receive from the Sun. These include eccentricity, axial tilt and precession.
How does eccentricity affect climate change
The orbit of the Earth changes shape every 100000 years,
sometimes the Earth’s orbit around the Sun is more circular(meaning interglacial periods) and sometimes the Earth’s orbit is elliptical(glacial periods).
How does axial tilt affect climate change
The angle of tilt changes every 40,000 years. The Earth is tilted
so the poles are 23 degrees from a vertical position, creating seasons north and south of the equator.The Earth is tilted sometimes away from the sun(greater difference in seasons), sometimes towards the sun(smaller difference in seasons).
Precession
The Earth wobbles on its axis- not perfectly rotating- on a cycle of 22000 years
How do asteroid collisions affect climate change
Large cosmic material like asteroids and comets releases lots of dust in the atmosphere, blocking solar radiation and leading to glacial periods
What do volcanic eruptions produce
Ash
Sulfur dioxide gas
How do volcanic eruptions affect climate change
If the ash and gas rise high enough, they are spread around the Earth by winds stopping sunlight reaching the Earth’s surface, cooling the Earth.
e.g. 1815 eruption of Tambora in Indonesia, temperatures so cold harvests failed and 20,000 people died- Year without a Summer in 1816
How does solar output variation affect climate change
Periods of lower solar activity(detected due to the lack of sunspots-black areas - on the sun’s surface) mean more glacial periods
Solar output changes in short cycles of about 11 years
Maunder Minimum was a period of reduced solar activity between 1645 and 1715 which coincided with the Ice Age
How do tree rings show climate change
Warmer and wetter weather shows greater growth since the tree ring is bigger,cooler or drier weather means rings are thinner
How do ice cores provide evidence of climate change
Scientists analyse bubbles in ice layers to see the amount of CO2 and they measure amounts of different oxygen atoms in water: to see the temperatures for each year.
The Little Ice Age
Between 1550-1850 temperatures were so low that rivers froze like in the London Frost Fairs
How do historical sources provide evidence of climate change
They give evidence of recent climate change e.g. old photos, drawings, written records
The Medieval Warm Period
A period of warming between 900 and 1300, with England warm enough to grow lots of grapes
The Medieval Warm Period
A period of warming between 900 and 1300, with England warm enough to grow lots of grapes
What is the atmosphere
A layer of gases above the Earth’s surface
What is the greenhouse effect
Gases in the atmosphere trapping heat from the sun
Gases in the atmosphere
Nitrogen is an important nutrient for plant growth
Carbon dioxide is taken in by plants which breathe out oxygen.
Oxygen is breathed in by animals, which breathe out carbon dioxide
Water vapour forms clouds
How does agriculture contribute to climate change
Mechanisation means more fuel is burnt
Rice paddies(flooded field for growing crops) and farming of livestock produces methane
More CO2 in atmosphere due to deforestation
How does the demand for energy enhance the greenhouse effect
Greater demand for energy due to greater population/technologies:energy produced through burning fossil fuels which releases greenhouse gases
How transport causes the enhanced greenhouse effect
Cars, lorries, ships and planes run on fossil fuels and are used more often, so release more greenhouse gases when they are burnt
How industrial processes cause global warming
Greater demand for production of consumer goods leads to industrial growth. Industry uses energy, while some industrial processes release greenhouse gases(e.g. cement is made from limestone, which contains carbon).
How global average temperature shows increasing climate change
A large increase in average global temperature from the 1950s to the present. The ten hottest years on record have occurred since 1998.
How arctic sea ice shows more climate change
Arctic sea ice has melted due to warmer global temperatures.
Over 90% of the world’s valley glaciers are shrinking