Topic 1- Global Atmospheric Pressure Flashcards
Where is the insolation greater? At the equator or at the poles?
At the equator.
How is heat transferred away from the equator?
Winds blow from areas of high pressure to areas of low pressure.
What are the names of three circulation cells in each hemisphere?
Hadley, Ferrel, Polar.
Fill in the gap:
Warm air rising creates a ………. pressure belt.
Low
Fill in the gap:
Cool falling air creates a ……….. pressure belt.
High
What happens at the equator?
Warm air rises—> cools and condenses—> forms clouds and rain.
Where is the air transferred after the equator?
The cool, dry air moves out to 30º north and south of the equator.
What happens at 30º north and south of the equator?
Cool air sinks—> high pressure belt created—> cloudless skies and very low rainfall.
What happens after the cool air sinks at 30º north and south of the equator?
Cool air reaches the ground surface and moves as surface winds either back to the equator (trade winds) or towards the poles (westerlies).
What happens at 60º north and south of the equator?
The warm surface winds meet the cool air from the poles. The warmer air is less dense than the cold air so it is forced to rise, creating low pressure and frontal rain.
What happens at the poles?
Cool air sinks, creating high pressure. The high pressure air is drawn back towards the equator as surface winds.
What are ocean currents?
Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions.
What is an example of surface currents?
The gulf stream. It brings warm water from the Caribbean and keeps Western Europe warmer than it would otherwise be.
What are surface currents and what causes them?
Surface currents are caused by winds and helps transfer heat away from the equator.
How is a current created
Water freezes at the poles—> water gets saltier —> increased density.
Increased density —> sinks —> warmer water flows in at the surface.
What is thermohaline circulation?
The cycle of cooling and sinking which moves water in a big loop around the earth.
What causes variations in climate?
The pressure belt caused by global atmospheric circulation.
How do Hadley and Ferrel cells create an arid climate?
The sinking air from the Hadley and Ferrel cells meeting causes high pressure and prevents rainfall. Therefore, there is low rainfall and temperatures are hot.
How do the two Hadley cells create a tropical climate?
Rising air from the two Hadley cells meeting causes low pressure and lots of rainfall. Therefore, temperatures are hot all the time and rainfall is high.
What creates a polar climate?
Sinking air from the Polar cells creates an area of high pressure at the poles. Temperatures are low all year round and there’s very little rainfall.
What is climate change?
Climate change is any significant change in the Earth’s climate over a long period.
What is the Quaternary period?
The most recent geological time period, spanning from about 2.6 million years ago to the present day.
How long is the interglacial period usually?
10,000 years
How long are the glacial periods usually?
100,000 years
When did the last glacial period end?
Around 15,000 years ago.
Define orbital changes?
Variations in the way the earth moves round the sun.
What is the stretch (eccentricity)?
The path of the Earth’s orbit around the sun.
How does the stretch (eccentricity) impact the earth’s orbit around the sun?
The path changes from an almost perfect circle to an elipse (oval) and back again about every 96,000 years.
What are natural causes of climate change?
Orbital changes.
Volcanic activity.
Solar output.
Asteroid collisions.
What is the tilt?
The earth’s axis is tilted at an angle as it orbits the sun.
How often does the tilt change?
The tilt changes over a cycle of about 41,000 years.
What is meant by the wobble?
The axis of the Earth wobbles like a spinning top.
How often does it wobble?
On a cycle of about 22,000 years.
How do orbital changes affect the climate?
The cycles affect the amount of solar radiation the Earth receives. If the Earth receives more energy, it gets warmer.
How does volcanic activity cause climate change?
Major volcanic eruptions eject large quantities of material, e.g. ash, into the atmosphere. Some of these particles reflect the sun’s rays back out to space, so the Earth’s surface cools.
How does solar output cause climate change?
The Sun’s output of energy is not constant. When solar output is reduced, the Earth’s climate may become cooler.
What was the Maunder Minimum?
A period of reduced solar activity between 1645 and 1715.
How do asteroid collisions cause climate change?
Asteroids hitting the Earth’s surface can throw up huge amounts of dust into the atmosphere. These particles prevent the Sun’s energy from reaching the Earth’s surface so global temperatures fall.
What are the three pieces of evidence for natural climate change?
Tree rings.
Ice cores.
Historical records.
How do tree rings show how the climate has changed over time?
By looking at the thickness of the rings, scientists can see what the climate was like each year. When it is warmer, the rings are thicker.
How do ice cores show how the climate has changed over time?
Ice sheets are made up of layers of ice. One layer is formed each year. By looking at the gases (e.g. carbon dioxide) trapped in the layers of ice, scientists can tell what the temperature was each year.
How do historical records show how the climate has changed over time?
Historical records like diaries can show what the climate was like by giving the number of days of rain or snow and the dates of harvests (an early harvest suggests warm weather).
