L1 - Atmospheric Circulation Flashcards
Where does the Earths heat come from and what does it do?
The sun’s radiation is the Earth’s source of heat. It causes warm air to rise leading to lower pressure at the surface.
What is the difference between climate and weather?
Climate: Long term patterns of temperature and precipitations
Weather: Daily environmental conditions
What are the two ways in which heat is globally redistributed?
Air movement
Oceanic currents `
What happens to sunlight when it hits darker surfaces on land?
It is absorbed and converted to heat
It only heats the surface and cools in winter
What happens to air when it is heated on land?
The air expands, becomes lighter and rises, leaving low pressure over large landmasses in summers.
What are the characteristics of the Hadley Cell?
From 0-30 degrees, thermally direct cell
Equator heated by sun, the hot air rises (due to low density), the air cannot hold moisture and causes a precipitation belt to form (LP, rain) (cumulonimbous clouds)
As the air moves to the pole the air sinks at 30 degrees leaving high pressure, clear skies and desert climates. (HP, sun)
What causes wind and why?
Pressure variations move air from high pressure to low pressure creating wind, it moves in a circular motion due to the Earth’s rotation. “Winds blow from high to low”
What are the characteristics of the Polar Cells?
Cold air sinks at the north and south poles which causes high pressure, lots of sunshine. (90 degrees)
Cooler air travels back to equator and warms up
At 60 degrees the cool air rises, condenses and cools causing LP and rain.
Thermally direct cell
What are the characteristics of the Ferrel Cells?
Thermally indirect - powered by other two cells
Between 30 and 60 degrees
High (30) to low (60) pressure.
What is the ITCZ?
Inter-tropical convergence zone
Permanent zone of low pressure
What are the Easterlies?
From 90 to 60 degrees winds blow from HP to LP.
From the east, hence easterlies) (Polar
What are the Trade Winds?
From 30 to 0 degrees, again HP to LP. (Hadley)
North easterly and south easterly
What are the Westerlies?
From 30 to 60 degrees at Ferrel cell (opposite to Hadley and Polar)
Why do the winds follow a curved path?
This is due to the Coriolis effect. Because the Earth is spinning on its axis the wind moves straight but curves as the Earth curves.
