Geography B edexcel paper 1

LOW pressure system

Warmth of Earth's surafce heats the air above.

Air begins to rise, which means less pressure on the earthe below.

As air rises it cools in the upper atmosphere and condeses forming clouds.

Regular areas with low pressure usually receive lots of annual rainfall.

HIGH pressure system

Cool air sinks back down to the Earth.

High pressure is formed 

Regular areas with high pressure are ARID areas

Receive low annual rainfall.

HADLEY CELL

Air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth’s surface, descending in the subtropics, and then returning equatorward near the surface.

This circulation creates the trade winds, tropical rain-belts and hurricanes, subtropical deserts and the jet streams.Hadley cell are the low-altitude overtuning circulation that have air sinking at roughly zero to 30 degree latitude.

FERREL CELL

Part of the air rising at 60° latitude diverges at high altitude toward the poles and creates the polar cell. The rest moves toward the equator where it collides at 30° latitude with the high-level air of the Hadley cell. There it subsides and strengthens the high pressure ridges beneath.

60-90 degree latitude.

POLAR CELL

Located near Earth's poles North and South.

Cold air sinks and travels inwards towards the equator.

Once at the equator the air rises, some travels back to the equator as part of the ferrel cell.

Some falls back down to the poles and continues the Polar cycle.

Milankovitch cycles

• Eccentricity- Orbit becomes eliptical so at times the earth is further from the sun causing it to be much cooler.
• Axial Tilt- Angle of the Earth's tilt changes so summers and winters are more extreme when this happens.
• Precession- The Earth sometimes wobbles on it's axis and it changes seasons slightly.

Solar Variation

• Amount of radiation the sun produces varies over time. Lower solar activity are likely to end in glacials.

Volcanism

• Large-scale eruptions can lead to lots of ash in the atmosphere, sometimes it's great it can block out the sunlight reducing global temperatures.

Surface impact

• Asteroids and comets can impact the Earth's surface and cause lots of ash blocking out sunlight- reduces global temperature.