Wind types by Group 2

Wind types

1. Wind types and the mechanisms of wind formation group 2

2. What exactly is wind? And why does it blow?

3. Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the Sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect .

4. In simple words … All molecules, even air molecules, have weight. What's generally labeled as the Earth's atmosphere extends about 80 kilometres above sea level. Imagine all the molecules that would fit in something that's 80 kilometres high and covers the whole planet's surface — together, this huge number of molecules weighs quite a bit. Gravity makes these molecules press downward on whatever is below them, so the closer you get to the Earth's surface, the more tightly packed are the molecules. Air under high pressure naturally flows toward areas of low pressure. The greater the difference in pressure, the faster the air flows. This is wind .

5. Air pressure differs from place to place and from day to day for two reasons : The earth's rotation : As the earth spins, it drags the atmosphere with it, but higher air is less affected by drag. These differing air speeds at different altitudes cause air to mix, forming turbulence, which causes wind down here near the Earth's surface. The S un : The S un varies in how much it heats air depending on time of day and the season (which hemisphere is closer to the sun). You know that the blazing midday sun is heating more air than it is during sunset, when the sun is low in the sky. As warmer air rises, the cooler air fills in and causes a breeze.

6. Wind force scale Historically, the Beaufort wind force scale (created by Beaufort) provides an empirical description of wind speed based on observed sea conditions. Originally it was a 13-level scale (0-12), but during the 1940s, the scale was expanded to 18 levels (0-17). There are general terms that differentiate winds of different average speeds such as a breeze, a gale, a storm, or a hurricane. Within the Beaufort scale, gale-force winds lie between 28 knots (52 km/h) and 55 knots (102 km/h) with preceding adjectives such as moderate, fresh, strong, and whole used to differentiate the wind's strength within the gale category. A storm has winds of 56 knots (104 km/h) to 63 knots (117 km/h).[20] The terminology for tropical cyclones differs from one region to another globally. Most ocean basins use the average wind speed to determine the tropical cyclone's category.

7. Wind types

8. Local winds Local winds occur on a small spatial scale, their horizontal dimensions typically several tens to a few hundreds of kilometres . They also tend to be short-lived lasting typically several hours to a day. There are many such winds around the world, some of them cold, some warm, some wet, some dry. There are many hazards associated with the winds. The main types of local winds are: Sea breezes and land breezes, Anabatic and katabatic winds, and Foehn winds.

9. Land and sea breeze Air over land heats and cools more quickly than air over water. So during the day, the air above land warms up and rises and cooler air moves in from over the ocean, which is what causes a breeze to come in from the water in coastal areas. During the evening, the temperature above land drops much faster than it does over the ocean, so this effect reverses and the wind flows out to sea.

10. A: Sea breeze (occurs at daytime), B: Land breeze (occurs at nighttime )

11. Global winds Large global wind systems are created by the uneven heating of the Earth’s surface. These global wind systems, in turn, drive the oceans’ surface currents. Unequal heating of the Earth’s surface also forms large global wind patterns. In area near the equator, the sun is almost directly overhead for most of the year. Warm air rises at the equator and moves toward the poles. At the poles, the cooler air sinks and moves back toward the equator. However, it is not this simple. Global winds do not move directly from north to south or south to north because the Earth rotates. All winds in the Northern Hemisphere appear to curve to right as they move. In the southern hemisphere, winds appear to curve to the left. This is known as the Coriolis effect, which is the apparent shift in the path of any fluid or object moving about the surface of the Earth due to the rotation of the Earth.

12. Trade Winds About 30° north and south of the equator, the warm, moist air that rose vertically cools and begins to sink. Here the sky is clear. There are few clouds and little rainfall. Winds are calm. These are called the horse latitudes, because when food ran out, sailors had to throw horses overboard. Deserts, such as the Sahara in Africa, are also common at 30°N and 30°S. At the horse latitudes some of the sinking air travels back toward the equator. The air moving back toward the equator forms warm, steady winds, known as the trade winds. The rising air at the equatorial regions and the sinking air at about 30°N and 30°S form huge convection current, known as a Hadley cell for the English meteorologist who first proposed their existence to explain the trade winds.

13. Westerlies and Easterlies Prevailing Westerlies – Some of the cool, sinking air continues to move toward the North and South. These winds are called the westerlies and are located between 40°to 60° latitude in both hemispheres. Polar Easterlies – In both hemispheres, the westerlies start rising and cooling between 50° and 60° latitude as they approach the poles. They meet extremely cold air flowing toward the equator from the poles and form the polar easterlies.

14. Thanks so much for your attention ! 