Glossary
Atmospheric Convection Cells
Large-scale patterns of atmospheric circulation involving the rising of warm, less dense air and the sinking of cool, more dense air.
Example:
The formation of a thunderstorm is a smaller-scale example of an atmospheric convection cell, where warm, moist air rises, cools, and condenses.
Coriolis Effect
An apparent force that deflects moving objects (like air and water currents) from a straight path due to the Earth's rotation.
Example:
The swirling pattern of hurricanes in the Northern Hemisphere, rotating counter-clockwise, is a visible manifestation of the Coriolis Effect.
Ferrel Cells
Mid-latitude atmospheric convection cells located between 30° and 60° latitude, driven indirectly by the movement of Hadley and Polar cells.
Example:
The temperate climates of many populated regions, like much of Europe and North America, are influenced by the complex air movements within the Ferrel Cells.
Hadley Cells
Atmospheric convection cells located between 0° and 30° latitude in both hemispheres, characterized by warm, moist air rising at the equator and dry air descending at 30°.
Example:
The world's major deserts, like the Sahara, are often found around 30° latitude due to the dry, sinking air of the Hadley Cells.
High Pressure
An atmospheric condition where air is sinking, leading to increased air density and higher pressure at the Earth's surface, often associated with clear skies.
Example:
A sunny, calm day is typically indicative of a high pressure system overhead, as sinking air prevents cloud formation.
Low Pressure
An atmospheric condition where air is rising, leading to decreased air density and lower pressure at the Earth's surface, often associated with cloudy or stormy weather.
Example:
The formation of a hurricane begins with a strong low pressure system over warm ocean waters, drawing in surrounding air.
Polar Cells
Atmospheric convection cells located between 60° and 90° latitude, characterized by cold, dense air sinking at the poles and warmer air rising around 60°.
Example:
The extremely cold and dry conditions at the Earth's poles are a direct result of the sinking, frigid air within the Polar Cells.
Trade Winds
Prevailing winds that blow from the subtropical high-pressure zones (around 30° latitude) towards the equatorial low-pressure zone, deflected by the Coriolis effect.
Example:
Historically, sailing ships relied on the consistent direction of the Trade Winds to cross oceans, especially for journeys between Europe and the Americas.
Uneven Solar Radiation
The differential distribution of solar energy across Earth's surface, with the equator receiving more direct sunlight and the poles receiving less.
Example:
This uneven solar radiation is why tropical regions are consistently warm, while polar regions remain cold, driving global weather patterns.
Wind
The movement of air from an area of high atmospheric pressure to an area of low atmospheric pressure, driven by pressure gradients.
Example:
A sea breeze, where cool air from the ocean moves inland, is an example of wind flowing from a higher pressure area over the water to a lower pressure area over land.