6.6 - Global Climate & Weather
The main climate regions of the world and their characteristics
The Earth is divided into distinct climate regions based on latitude and atmospheric patterns. Each zone has unique characteristics influenced by air pressure, temperature, and precipitation patterns, shaping the weather experienced in different parts of the world.
Characteristics of global climate zones
| Climate zone | Latitude range | Key characteristics |
|---|---|---|
| Polar | 90° north and south of the Equator | Cold, sinking air from the Polar cell creates high pressure. Dry, icy winds dominate. |
| Temperate | 50° to 60° north and south of the Equator | Warm air from the Ferrel cell meets cold air from the Polar cell, forming low pressure and frequent rainfall along weather fronts. This is typical of regions like the UK. |
| Subtropical | 30° north and south of the Equator | High pressure from sinking air where Hadley and Ferrel cells meet creates dry conditions, forming desert belts like the Sahara in Africa. Daytime temperatures can soar above 40°C. |
| Tropical | 0° at the Equator | Low pressure where Hadley cells meet causes rising air, leading to heavy, regular rainfall and frequent thunderstorms in areas like South East Asia and northern South America. |
The role of atmospheric circulation cells in shaping climate zones
Atmospheric circulation cells are large-scale patterns of air movement in the Earth's atmosphere. They play a crucial role in determining the climate of different regions by influencing air pressure, temperature, and precipitation distribution.
The three main atmospheric circulation cells
- Hadley cell - Operates between 0° and 30° latitude. Air rises at the Equator due to intense heating, creating low pressure and heavy rainfall. It sinks at around 30°, forming high pressure and dry conditions in subtropical zones.
- Ferrel cell - Found between 30° and 60° latitude. Air movement is influenced by the meeting of warm and cold air masses, leading to low pressure and wet weather at around 60°, often seen in temperate regions.
- Polar cell - Extends from 60° to 90° latitude. Cold air sinks at the poles, creating high pressure and dry, windy conditions typical of polar climates.
The boundaries where these cells meet create distinct weather patterns, such as fronts in temperate zones where warm and cold air collide, resulting in rainfall.
Extreme temperature conditions in different global locations
Some places on Earth experience temperature extremes due to their geographic location, altitude, or atmospheric conditions. These extremes highlight the diversity of climates across the planet.
Record-breaking temperature locations
- Coldest location - Vostok, Antarctica - On 21 July 1983, a temperature of -89.2°C was recorded at the Russian research station. Its high altitude of around 3500 metres contributes to its frigid conditions.
- Hottest location - Al-Aziziyah, Libya - On 13 September 1922, a scorching temperature of 57.8°C was recorded in Libya. Positioned at 32° north of the Equator, its arid surroundings create extreme temperatures.
Extreme wind and precipitation conditions around the world
Beyond temperature, certain locations experience extraordinary wind speeds and precipitation levels, driven by geographic features and atmospheric dynamics. These extremes significantly impact local environments and communities.
Windiest locations
- Commonwealth Bay, Antarctica - Known for winds regularly surpassing 240 kilometres per hour, with an average annual speed of 80 kilometres per hour. These powerful winds result from gravity pulling cold, dense air down steep slopes.
- Wellington, New Zealand - The strongest gust of wind recorded was 248 kilometres per hour. Winds are funnelled through the narrow strait between mountains, with gale-force conditions occurring on over 175 days annually.
Driest locations
- Death Valley, USA - Receives an average of just 60 mm of rain per year. Storms lose moisture over mountain ranges before reaching this area, leaving it extremely arid.
- Aswan, Egypt - Near the Tropic of Cancer, it averages a mere 0.861 mm of rainfall annually, due to persistent high pressure in the subtropical zone.
- Atacama Desert, South America - Sees an average of 15 mm of rain per year. Located in the rain shadow of the Andes, and with cold ocean currents limiting moisture, it remains one of the driest places on Earth.
Wettest locations
- Mawsynram, India - Experiences an average annual rainfall of 11,871 mm, with around 80% occurring during the monsoon season. Its location in a mountainous region enhances rainfall.
- Ureca, Equatorial Guinea - Situated on Bioko Island, it receives about 10,450 mm of rain yearly, driven by its tropical position near the Equator where rising air creates consistent heavy precipitation.