Unit 4 - Climate - Global Controls Flashcards
What are the 4 main layers of the Earth’s atmosphere
- Troposphere: Most weather processes occur in this layer, varying between 8km and 12km in height. Lower layers receive Earth’s heat, causing temperatures to drop by 6.5°C every 1000m.
- Stratosphere: Increase in temperature with height due to absorption of solar radiation by ozone molecules.
- Mesosphere: Above the stratosphere and below the thermosphere, temperatures fall with height due to lack of energy absorption.
- Thermosphere: The outermost layer, above 90km, where air becomes extremely thin and temperatures increase steadily with altitude.
What is the atmospheric heat budget?
The atmospheric heat budget is the balance between incoming solar radiation (insolation) and outgoing radiation from the planet.
Why are some areas of the planet colder than others?
Not all parts of the planet receive the same amount of energy. The tropics have an energy surplus whilst the higher temperate and polar latitudes have an energy deficiency.
An area of energy surplus gains more from insolation than is lost by radiation.
An area deficient in energy loses more by radiation than is gained by insolation.
This imbalance in energy distribution sets up a transfer of heat energy via winds and ocean currents from the tropics to higher latitudes.
How are the three main convection cells created and what are their names?
This global transfer of energy results in global low and high pressure belts. It also results in the planetary wind systems associated with the Earth’s three major convection cells: the Hadley, Ferrel and Polar cells. This tricellular model controls the atmospheric movements and the redistribution of heat energy.
Outline the Hadley cells’ functions.
The largest of the three cells and two surround the equator. Heat rises up to about 18km across the troposphere to higher latitudes and then eventually cools, descends and returns to the equator.
Outline the Polar cells’ functions
The smallest of the three cells and there are one on each pole. Cold dense air descends in the centre of the polar regions and flows to low levels (around 60-70 degrees North or South). As the air leaves the polar region it begins to heat up which causes it to rise and return to the polar region at high altitudes.
Outline the Ferrel cells’ functions.
In between the Polar and Hadley cells and is in fact not controlled by temperature. This cell is forced to move like a gear in the opposite direction of air flow in the other surrounding cells. This transports heat from equator to pole leading to semi-permanent areas of high and low pressure.
What is the Coriolis effect?
Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. This is caused due to the Earth’s rotation being faster at the equator compared to the poles
How do ocean currents affect the climate?
Warm currents tend to make areas close by warmer and wetter, whilst the cold currents make areas nearby colder and sometimes drier. An example of warm currents is the North Atlantic Drift or Gulf Stream that flows off the West coast of the UK. An example of a cold current is the Western Australian current.
How does proximity from the ocean (continentality) affect the climate?
The land surfaces of continents and oceans respond differently to solar radiation. Continental land masses heat up quickly during the Summer and cool down rapidly in the Winter. This results in a greater annual temperature range. Oceans heat up more gradually during the Summer but retain this heat during the Winter. This leads to a smaller annual temperature range.
How does altitude affect the climate?
Temperatures decrease with altitude. The average global reduction of temperature with altitude within the troposphere is 6.5°C per 1000m. This is known as the environmental lapse rate. If dry air is forced to rise over mountains such as the Andes, the temperature fall can be as much as 10°C per 1000m. If the air becomes saturated and condensation occurs there is a release of latent heat, which reduces the rate of cooling to 5°C per 1000m.
