Global Climate Patterns Flashcards
How is Moisture held in the air?
- Air rising at the Equator is hot so it evaporates moisture from the oceans (remember, hot air can also hold more moisture)
• As it rises, it cools (adiabatically)
• What happens to air’s ability to hold water when it cools?
• It decreases – reaches it dew point and rain falls
What is the Intertropical Convergence Zone (ITCZ)?
Places around the equator where their is massive amounts of rainfall and these systems are usually associated with very low pressure (equatorial lows ) (<1000 hPa) – ‘depressions’
What happens to the air’s moisture as it travels away from the ITCZ and reaches the end of the Hadley Cell?
- It loses its moisture, sinks back down, becomes warmer, and has high pressure – all result in dry air
Fill in the labels in the ‘Climate patterns and the main cells’ diagram
https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing
Which Climate cells is Australia part of?
- Australia lies within 2 climate cells
• Most of it (70%) sits within a Hadley Cell
• The bottom half is in a Ferrel Cell
What are the main wind
directions in Australia’s Climate cells?
Hadley Cell: - Coming from the south-east - Easterly direction because it is coming from the pacific Ferrel Cell: - Traveling to the south east - Coming from the South-West
What are the main land masses in Australia to cause air uplift and rain?
- Australia doesn’t have massive mountains and air is generally free to move over the whole continent
- But, the Great Dividing Range does force out most of the moisture from the trade winds
- In the west and south, any moisture is coming from Ferrel westerlies when they hit land
How does the tilt of the Earth during different seasons affect the positioning of the Climate Cells over Australia?
- In summer, even more of Australia is in a Hadley Cell as the Earth tilts up
- In winter, the proportion of Australia in a Hadley Cell reduces as the Earth tilts down
Due to the tilt of the Earth in summer, what happens to the climate?
- The ‘high’ between the Hadley and Ferrel Cells is at a low latitude
- The east coast gets most of its rain as Hadley Trade Winds dominate the continent
- Not much Ferrel wind contact, so less rain in south and west
Due to the tilt of the Earth in winter, what happens to the climate?
- The ‘high’ between the Hadley and Ferrel Cells is at a higher latitude
- We get stable dry highs over most of the north of the continent
• The south and west get wet Ferrel winds
How do the seasons effect the Climate cells and the Equator?
- As the Earth tilts during the seasons, the effective position of the Equator also changes.
- Consequently, the Intertropical Convergence Zone is a band that extends from about 5 Degrees south and north of the Equator, to encompass these shifts
Why is rain fall in the tropics of Australia not high during winter?
- In Australia’s winter, northern hemisphere tropical zones are on the effective Equator and so rainfall in the tropics is generally not high.
Why is rain fall in the tropics of Australia higher during summer?
- In Australia’s summer, southern hemisphere tropical zones are on the effective equator and this is when most rainfall occurs in these areas, like Cairns and Darwin.
What effect does the Climate Cells have on ocean currents?
- The Trade Winds not only affect air flow, they also drive ocean currents
- They blow warm water from the surface of the ocean from east to west
- The displacement of warm water in the east creates a vacuum -> which is filled by underlying denser colder water
- As a result we get convection currents – just like in the atmosphere
Fill in the ‘Effect of Trade Winds on The Ocean Currents’ Diagram
https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing
