2.2 The global energy budget Flashcards

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1
Q

What is the global energy budget?

A

The atmosphere is an open energy system receiving energy from both Sun and Earth

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2
Q

What are the variations in the receipt of solar radiation and why?

A
  • Due to the tilt of the Earth and its orbiting around the Sun, with latitude, there is a positive budget in the tropics and negative at the poles
  • It is also due to the tilt of the Earth that the Southern hemisphere in January is summer, July winter and vice versa.
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3
Q

Define thermal equator

A

An imaginary line round the earth running through the point on each meridian with the highest average temperature

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4
Q

What is the annual temperature pattern (thermal equator)?

A
  • In January, the thermal equator is further South
  • In July, the thermal equator is closer to the actual equator
  • In general, there’s a decline in temperatures northwards from the Tropic of Capricorn
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5
Q

How is balance achieved between the negative energy budget (at the poles) and positive energy budget (at the tropics)?

A

By the horizontal transfer of energy from the equator to both poles by winds and ocean current to compensate for differences in global insolation. Warm air rises at the equator, spreads northwards and southwards and then sinks

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6
Q

What does the surface pressure belt consist of?

A
  • Equatorial low pressure trough
  • Sub-tropical high pressure belt
  • Sub-Antarctic and sub-Polar areas
  • Polar highs
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7
Q

Why does the equatorial low pressure trough have low pressure?

A

This is an area of low pressure because it is an area of high temperature and humidity due to the sun heating it directly. In the northern hemisphere in July, the belt is north of the equator whereas in the southern hemisphere during January

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8
Q

Define Intertropical Convergence Zone (ITCZ)

A
  • The area encircling the earth near the equator where the northeast and southeast trade winds come together.
  • The convergence of warm, moist air over the equator transports large volumes of air aloft, to the top of the troposphere. This air is confined vertically by the base of the stratosphere and thus spreads out north and south toward the poles
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9
Q

Define doldrum

A

Refers to the part of Atlantic ocean/Pacific affected by ITCZ

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10
Q

How does pressure vary at the sub-tropical high pressure belts (30 degrees N and S)?

A
  • In SH continuous about 30 degrees latitude
  • In NH discontinuous because of the land
  • Over oceans, high pressure occurs as discrete cells, the Azores and Pacific Highs
  • Over continental areas, southwest USA, southern Asia and Sahara, major fluctuations: high pressure in winter and low in summer due to overheating
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11
Q

How does pressure vary at the sub-Arctic or sub-Polar areas (temperate latitudes)?

A
  • In the northern hemisphere, there are strong winter low pressure zones over Icelandic and oceanic areas but over Canada and Siberia, there is high pressure due to the coldness of the land.
  • In summer, high pressure is reduced, especially over continental areas
  • In SH, it does not vary as much because here is more ocean in the Southern Hemisphere- and oceans do not vary in pressure or temperature as much as land does
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12
Q

What’s the pressure at the poles?

A
  • Polar highs

- Pressure is high relatively throughout the year, especially over Antarctica due to the coldness over the landmass

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13
Q

How does the wind move?

A

From high pressure to low pressure and also due to the Coriolis effect, tends to follow more east-west trends rather than north-south trends.

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14
Q

Define Trade Winds

A
  • In the NH, air blows from the northeast to the southwest
  • In the SH, blow from the southeast toward the northwest
  • These are Trade Winds
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15
Q

Define monsoon

A

Reversing wind systems/direction

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16
Q

How is monsoon induced?

A
  • Induced by Asia which causes wind to blow outwards from high pressure in winter but pulls the southern trades into low pressure in summer => influenced by the reversal of land and sea temperatures between Asia and Pacific during winter and summer
  • In winter, surface in Asia can be as low as -20 degrees and surrounding oceans have temp of 20 degrees
  • During summer, land heats up more quickly => 40 degrees while summer 27 degrees
17
Q

Define Upper Westerlies

A

Prevailing winds at the upper latitudes (between 30 and 60) that travels from west to east

18
Q

Define Easterlies

A

Winds that travel from east to west

19
Q

How is land-sea breeze induced?

A
  • Blowing from the cooler sea (high pressure) in summer to warmer land (low pressure)
  • In winter, air flows out of the cold land mass (high pressure) to warm water (low pressure)
20
Q

What are the 3 cells the tri-cellular model consist of?

A
  • Polar
  • Ferrell
  • Hadley
21
Q

What happens in the Hadley cell?

A
  • At the equator the sun shines directly and warms the surface => warm air rises => low pressure
  • In the subtropics (20-30 N and S) air sinks because it’s colder and denser, it then returns to the tropics to replace rising air. Cycle repeats.
22
Q

What happens in the Polar cell?

A

Warm air rises at lower latitudes and moves pole wards. Air reaches the polar areas cooled considerably and descend as cold dry high pressure area

23
Q

What happens in the Ferrell cell?

A
  • Warm air is transferred to high latitudes and shifts cold air back to the subtropics where it is warmed
  • It exists due to the other 2 cells and it mirrors the other cell movements
24
Q

What is the Coriolis effect?

A

The deflection of moving objects caused by easterly (West to East) rotation of the Earth

25
Q

Explanation of the Coriolis effect

A
  • Near the equator where the Earth is widest, the outer edge of the Earth’s atmosphere is moving faster than it does around the poles => atmosphere gains a more west to east spin at the equator
  • Flies upwards to the NH => to the right/east (nhin tu pole xuong equator)
  • Flies downwards to the SH => to the left/west
26
Q

Define jetstreams

A

Strong, regular winds which blow in the upper atmosphere (abt 10 km above the surface), they blow between the poles and tropics at speed from 100-300km/h

27
Q

Define Rossby waves

A

Meandering rivers of air formed by westerly winds. They are formed by major relief barriers such as the Rockies, the Andes by thermal differences and uneven land-sea interfaces

28
Q

How does the Rossby wave work?

A
  1. Tropical air moves towards the Poles because heat tends to flow from low to high latitudes
  2. When air hits a barrier, usually a mountain, this changes its trajectory-heading north
  3. Due to Coriolis effect, the air moves South and then North again
29
Q

Why are jetstreams and Rossby waves important?

A

Mixing warm and cold air

30
Q

Factors affecting the climate

A
  • Altitude
  • Latitude
  • Distance from sea
  • Ocean currents
  • Prevailing winds and air circulations
31
Q

How does latitude affect the climate?

A
  • High temps are recorded at low latitudes in the tropics N & S of the equator
  • A decrease in temp between Equator and poles
  • Explanation: The sun’s ray are more concentrated at the Equator because they hit the Earth directly. As you go away from the equator, the curve of the earth means that the same rays have to spread over a larger surface area => doesn’t heat up as much
32
Q

How does ocean currents affect the climate?

A
  • Warm currents from equatorial regions raise the temps of polar areas (with the aid of prevailing westerly winds). However, only noticeable in winter. e.g. North Atlantic Drift raises temp of northwest Europe
  • Areas made colder by ocean currents. e.g. Labrador current off the northeast coast of North America reduce summer temp, if only winds blows from sea to land
33
Q

Define gyres

A

The dominant pattern of surface ocean currents that is a roughly circular flow. Pattern is clockwise in NH and vice versa

34
Q

What’s the general movement of currents?

A
  • Warm - away from equator

- Cold - towards the equator

35
Q

How does distance from the sea affect the climate?

A
  • Difference in the specific heat capacity/continentality
  • Land heats up and cools more quickly than sea
  • In land: warm summer, cool winter
  • In coastal areas: cool summer, warm winter
36
Q

How does altitude affect the climate?

A
  • For every 100m you ascend, the air temp drops by 1 degree
  • Temperature decreases with height because most of the solar radiation passes through the atmosphere with little or no effect - that radiation is absorbed by the solid Earth surface and is transferred to the air above the surface by conduction.
37
Q

How does air circulation affect the climate?

A
  • Air rises at the equator due to the amount of insolation received
  • As air rises, it makes cumulonimbus (thunder and rain) as it cools down in the tropical areas
  • Once it has cooled it becomes denser and sinks making an area with high pressure and no clouds - deserts
  • In temperate zones, warm air (equatorial regions) meets cool air (polar regions) , the warm air slowly rises above the cold air, forming a low pressure zone. As the rising warm air reaches higher elevations, the liquid in it condenses and forms clouds and rain. Cool air rushes in to fill the low pressure zone, pushing more warm air up and creating a cycle that can result in high winds and storms.