Wind is the movement of air across Earth’s surface. It is caused by differences in atmospheric pressure. The global atmospheric circulation pattern is determined by temperature differences, especially the difference between heating at the equator and the poles, and by the Earth’s rotation. Winds shape regional climate and influence daily weather by transporting heat and water.
Various human activities and environmental phenomena can influence wind patterns, including:
- The burning of fossil fuels, agricultural activities, and deforestation, which increase the concentration greenhouses gases in the atmosphere, increasing Earth’s average temperature. The Arctic has warmed more than lower latitudes, and as a result the temperature difference between the mid-latitudes and the polar regions has become reduced, which has changed the path of the northern hemisphere jet stream so that it now moves north and south over a greater range of latitudes. As the atmosphere continues to warm, we expect to see much deeper north-south waves, which will cause a slowing down, or even blocking, of the jet stream. This could result in weather systems that persist for much longer than would be considered normal over any particular region.
- Urbanization, which increases the amount of sunlight that is absorbed, instead of being reflected by the Earth’s surface. These urban heat islands increase local temperatures.
- Over millions of years mountain building alters atmospheric circulation For example, some of the wettest places on Earth are where warm moist air cools as it is forced to rise over the mountains, causing the water vapor to condense as clouds and be released as rain or snow. Once the air is past the peaks of the mountain range, precipitation then deceases because the air has depleted much of its water vapor and because the descending air warms enabling it to carry more water vapor. Thus, the downwind side of a mountain range is typically much drier than the upwind side, and is said to be in a rain shadow.
- Over millions of years, changes in the distribution of continents and oceans can alter where and how much sunlight is absorbed or reflected by the surface of the Earth. This differential heating influences the direction and strength of wind patterns.
Wind affects various Earth system processes and phenomena, including:
- Regional temperatures, humidity, and precipitation patterns.
- The distribution and concentration of clouds, pollutants, and airborne particles.
- Surface currents in the ocean. Wind pushing on the surface of the water is one of the primary drivers of global patterns of ocean circulation.
- Causing erosion of sediments on the surface of the Earth.
- Spreading embers from fires, increasing the size of affected areas.
Can you think of additional cause and effect relationships between wind and other parts of the Earth system?
Visit the atmospheric circulation, ocean circulation, and the temperature pages to explore more connections between the atmosphere and global changes.
Links to Learn More
- National Weather Service: Global Circulations
- National Weather Service: The Jet Stream
- National Center for Atmospheric Research: Conduction
- National Center for Atmospheric Research: A Global Look at Moving Air: Atmospheric Circulation
- NOAA: Weather Systems and Patterns
- NOAA: What are sea breezes and why do they occur?