Atmosphere, Weather and Climate:
The Structure of the Atmosphere:
The Red Bull Stratos Website page has lots of information on the structure of the atmosphere.
Structure of the Atmosphere.doc
Task 1
1) Create your own version of the diagram above and describe the different layers of the atmosphere that a space rocket would pass through on its way to space. Include information on altitude, temperature change, air pressure.
2) Create an acronym that will help you remember the different zones in the atmosphere.
Factors affecting the climate:
1) Energy from the Sun
The energy received from the sun is the driving force behind our climate.
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| Diagram 1 |
**Shortwave radiation** (Yellow on the diagram above) from the Sun enters the surface-atmosphere system of the Earth and is ultimately returned to space as longwave radiation (Red on the diagram). A basic necessity of this energy interchange is that incoming solar insolation and outgoing radiation be equal in quantity. (From PhysicalGeography.net)
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| Diagram 2: Annual (1987) pattern of solar radiation absorbed at the Earth’s surface |
Task 2:
1) What type of the radiation is emitted by (i) the sun, (ii) the earth?
2) Describe the earth’s energy budget shown in Diagram 1.
3) Describe the global variation in the amount of solar energy received around the world as shown in diagram 2.
Latitude
Task 3:
Use diagrams 1,2, 3 and 4 to help answer the following questions.
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| Diagram 3: The Impact of Latitude on Temperature. |
4) Why is there less solar energy arriving at the poles than the equator?
5) Why is the most energy received in a band between the tropics rather than in a narrow band along the equator?
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| Diagram 4: The earths orbit around the sun. |
The Tri- Cellular Model
The equator is the warmest location on the Earth. This area of greater heat rising air and low air pressure, the intertropical convergence zone (ITCZ ).
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The Inter Tropical Convergence Zone (ITCZ)
The zone of low pressure created by warm air rising close to the equator is know as the Inter Tropical Convergence Zone (ITCZ). The ITCZ migrates north and south of the equator with the seasons.
Click on the link below to explore the migration of the ITCZ and its impact on global weather patterns.
The ITCZ’s location varies throughout the year and while it remains near the equator, the ITCZ over land drifts farther north or south than the ITCZ over oceans. This is due to greater variation of land temperatures. The location of the ITCZ can vary as much as 40° to 45° of latitude north or south of the equator based on the pattern of land and ocean. Despite these variations the ITCZ relates closely to the altitude of the sun and marks the point where the sun is highest in the sky.
The Hadley Cell
The Intertropical Convergence Zone draws in surface air from the subtropics.
When this subtropical air reaches the equator, it rises into the upper atmosphere because of convection.
It reaches the top of the troposphere and then begins flowing horizontally to the North and South Poles.
Coriolis force causes the deflection of this moving air in the upper atmosphere, and by about 30° of latitude the air begins to flow from west to east.
This zonal flow is known as the subtropical jet stream.
Air begins to accumulate because it can no longer move towards the pole. As a result some of the air sinks to the earths surface producing an area of high pressure over the tropics.
When the air sinks to the earths surface at the tropics some of it moves back towards the equator completing the Hadley Circulation Cell.
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| 1) Warm air rises and creates a low pressure zone close to the equator. As it rises, the air cools and condenses forming cloud and resulting in the high levels of convection rainfall associated with equatorial regions.2 a&b) At the Tropopause the air begins to move pole-wards.3) The cold, dry and more dense air decends over the tropics creating a bands of high pressure at close to the tropics.4) Air is drawn back towards the equator creating completing the circulation cell. |
As this air returns to the equator it is also deflected by Corriolis Force. The result is the NE Trade Winds (northern hemisphere) and the SE Trade Winds. (Southern hemisphere)
The surface air moving from the tropics to towards the poles is deflected producing the Westerlies.
Between the latitudes of 30 to 60° North and South, upper air winds blow generally towards the poles.These winds are deflected to the right by Corrioils force and form polar jet stream at roughly 60° North and South. 
On the Earth’s surface at 60° North and South latitude, the subtropical Westerlies collide with cold air traveling from the poles.
This collision results in frontal uplift and the creation of the subpolar lows or mid-latitude cyclones.
A small portion of this lifted air is sent back into the Ferrel cell after it reaches the top of the troposphere. Most of this lifted air is directed to the polar vortex where it moves downward to create the polar high.
Task:
Look again at the animation of global winds. Using the aid of diagrams and text, explain the pattern shown.
How is this Tri Cellular model reflected on earth? How does it effect the climate of our planet?
Weather and Climate:
What’s the difference? Write a definition of each one and post it to the discussion board.
Climate:
As you have learnt, the earths climate is determined by the the circulation of air in the atmosphere. However there are a number of other factors that determine the local climate for any location on the earth. Remember the Tri-Cellular Model is just that, a model, based on a homogenous planet. Since the earths surface is not homogenous, it makes sense that the model is not perfect.
The map below confirms this. How does the map below differ from what the Tri Cellular model predicts? We will be studying the different climatic zones (Biomes) in more detail
Factors that affect climate and temperature:
Click on the link above that will take you to the BBC Bitesize website and read through the information before taking the test at the end.
You should be able to explain how latitude, altitude, the distance from the sea, ocean currents and the prevailing wind all have an impact on an regions climate.
The Effect of Altitude on Temperature:
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| Kilimanjaro is in Tanzania. It is 5,895 m high(photo from http://captainandclark.com) |
Here is an exerpt from a Q & A session on the website onthesnow.com. It explains how and why temperature falls with altitude.
Question:
How does elevation affect temperature? Is there a simple way to estimate the summit temperature if I know the temperature at the base?
– Mr. Mears
Whistler, British Columbia
Answer:
Like a lot of things in meteorology it’s fair to say you can “kind of” estimate the summit temperature by recording the temperature at the mountain’s base.
But before we get into numbers, it’s important to remember the temperature can vary for a number of different reasons.
Shade, sun, nearby buildings (or lack of them) and inversions (colder air sinking into valleys because it’s heaver than warm air) can all influence the temperature.
These caveats aside, here’s the scoop on temperature and elevation. If there is NO snow (or the dreaded rain) falling from the sky and you’re NOT in a cloud, then the temperature decreases by about 9.8 degrees Celsius per 1,000 meters.
However, if you’re in a cloud, or it is snowing/raining, the temperature decreases by about 6 degrees Celsius per 1,0000 meters.)
Confusing?
I know. So here’s a handy chart to visualize the temperature decrease with elevation:
Temperature and elevation
Just remember that temperature changes 5.4F/1,000ft (9.8C/1,000m) if it’s dry and 3.3F/1,000ft (6C/1,000m) if it’s snowing.
Enjoy your time on the hill!
The Effect of Ocean Currents on Climate
Exam Questions
(i) Describe the distribution of areas with a tropical rain forest ecosystem. [2]
(ii) Describe the distribution of areas with a tropical desert climate. (2)
(iii) Explain why areas of tropical rain forest have a high annual precipitation. [3]
(iv) Explain why parts of some continents, such as South America and Africa, experience a tropical rainforest climate whilst other parts experience a tropical desert climate. [7]