Where does the wind come from?

What is wind? Where does it come from and why does it blow? Why are storm winds so strong? Are winds on other planets like those on Earth? LandRead on to find answers to these simple questions and more!

Earth, wind and water

The simplest definition of wind is moving airWind is generated by uneven pressure in the atmosphere, which is caused by uneven heating by the Sun, Earth and oceans.

The air closest to the ground is also the warmest, but warmer air rises and cooler air sinks. At the same time, Earth's rotation causes air masses to move toward and away from the poles due to the Coriolis effect. Atmospheric friction from our planet's rotation causes air masses and storm systems to spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Between these two powerful engines of circulation, Earth's atmosphere is constantly moving and changing.

The Earth has five major wind zones, organized by latitude. From the poles to the equator, we have the polar easterlies, the westerlies, the mid-latitude trade winds, and the calm winds.

Prevailing winds are air masses that travel in a single direction over a specific area of ​​the Earth. Generally, prevailing winds blow from east to west rather than north to south. Trade winds are permanent east-west prevailing winds that circulate between the horse latitudes and the equator. The horse latitudes are a high-pressure region roughly overlapping the tropics, which (because high pressure pushes outward) tends to “shed” air masses. Winds to the south are pushed toward the equator, while those on its northern side become westerlies, which are deflected toward the poles, dragging tropical and extratropical cyclones along with them.

The term “horse latitudes” comes from a bit of nautical history. During the period when the Spanish colonized America and the West Indies, many ships carried horses as part of their cargo. About thirty degrees from the equator, the winds tend to be calm and pressure tends to be high, meaning that weather systems don't linger. (This is one factor that pushes hurricanes away from the poles and closer to temperate latitudes.) Clear weather is pleasant, but if the winds aren't blowing, a sailing ship can be grounded for days or weeks. Crews in calm weather often went without drinking water. According to legend, faced with the possibility of dying of thirst, sailors on these troubled ships would sometimes throw the horses they were carrying overboard.

Storm winds

What causes hurricanes? Why do the winds in hurricanes and tornadoes have such high speeds? If a hurricane is a tropical cyclone, is there such a thing as a temperate cyclone? The answer to all of these questions lies in how the Coriolis force asserts itself in the atmosphere. Spiraling wind currents develop into convection cells and then into storms that can explode in intensity within hours.

Hurricanes

Hurricanes, also known as tropical cyclones, form only in the tropics, where the temperature in the top 50 meters of ocean water reaches at least 26 °C (80 °F). In the case of hurricanes that form in the Atlantic Ocean, westerly winds carry warm, dust-laden air from the Sahara into the Atlantic. As the wind passes over the ocean surface, some of the water evaporates (turns into water vapor) and rises. As it rises, it cools and creates a low-pressure area.

Some water droplets condense and form nuclei around desert dust particles, creating towering storm clouds called cumulonimbus. As more and more droplets collide, they fall as rain. Meanwhile, friction between the droplets and dust granules produces lightning and thunder. Sometimes this simply creates powerful storms, but when the Coriolis effect takes over, a vortex can form that turns a storm front into a hurricane.

As air is sucked into the storm's low-pressure center, momentum increases, the vortex narrows, and wind speeds increase. The Coriolis effect shapes those spiraling winds, creating the characteristic shape of a hurricane. In fact, hurricanes rely so heavily on the Coriolis effect that within five degrees of the equator, where the effect is much weaker, hurricanes have a hard time forming. Eventually, once a hurricane has exhausted its energy over land, the storm will dissipate, its remnants returning to sea.

Temperate cyclones and jet streams

The same Coriolis forces that create vortices in Earth's atmosphere in the tropics also create vortices in temperate latitudes, often over land, called temperate cyclones or extratropical cyclones. Like hurricanes, these mid-latitude storm systems often have a counterclockwise circulation and even a distinct “eye.” They are also just as powerful as hurricanes. Extratropical cyclones were responsible for the Great Blizzard of 1888, the Great Storm of 1889, and the Great Storm of 1890. Sinking of the Edmund Fitzgeraldand the Perfect Storm of 1991.

A narrow, fast-moving wind current called the polar current. jet streamCirculating at the margins of the polar vortex, it affects the path of storm fronts and extratropical cyclones. A major storm path for extratropical cyclones produces the Chinook winds, which originate and carry strong thunderstorms known as Alberta clipper winds that sweep across the Canadian interior and upper Midwest. If a northeasterly wind, such as the jet stream, catches a storm system and directs it toward the East Coast, we often call that storm a nor'easter.

Atmospheric rivers

In 2022, the eruption of an underwater volcano in the South Pacific spewed enough water vapor into the atmosphere to alter its composition and influence weather patterns around the world. Prevailing wind currents carried that moisture thousands of miles, creating continent-spanning cloud channels that could drop a month’s worth or more of rain in just a few hours. These storms, called atmospheric rivers, are almost too big to be called storms. When an atmospheric river follows a path over land, the monsoon-class rainstorms it can generate are among the most intense rainfall events known.

Winds on other planets

What is the wind like on other planets? Mars and other rocky planets with atmospheres have winds very similar to those on Earth. Photographs from the spacecraft we have sent to orbit and explore Mars show that even with Mars' thin atmosphere, its winds can carry enough particles to erode rocks. raise sand dunes-and Burying solar panels on a Mars lander into ultra-fine powder.

In the case of a gas giant, the situation is different. Based on what we know about Jupiter and its relatives, gas giants do not have surfaces like Earth's, with a defined transition between solid crust and atmosphere. Wind bands surround gas giants, moving at hundreds, even thousands, of miles per hour. NASA's Juno spacecraft captured this image of Jupiter's wind belts in September 2023:

Gas giants are almost perfect spheres, so their wind belts can start to have strange effects on the outer layers of planets, sort of like a spirograph. In our own solar system, Jupiter and Saturn have amazing geometric storms at their poles.

Saturn's polar hexagon and the titanic cyclones around Jupiter's poles are generated by the same forces that circulate Earth's atmosphere and oceans.

The solar wind

Powered by internal fusion engines, stars like ours Sun They convert their own mass into energy, which they radiate towards space The solar wind is created by the outward expansion of plasma (a collection of charged particles) from the Sun's corona (the outermost layer of its atmosphere). This plasma is continuously heated by the Sun's internal fusion engine, so much so that its energy is sufficient to push it outward against the Sun's gravity. It then travels along the Sun's magnetic field lines that extend radially outward. The same radial lines determine the direction of a comet's ion tail.

Normally, Earth's magnetic field shields us from most space weather and solar wind. However, the Sun's surface activity waxes and wanes over an 11-year period. solar cycle (which will reach its next peak in 2025). Sometimes, turbulence in the Sun's outer layers creates “coronal holes,” magnetic disturbances so large they could swallow the Earth whole. When those magnetic disturbances finally equalize, they often release a coronal mass ejection. Moving at about a million miles per hour, these plasma blobs can reach as high as 100 million miles per hour. Marscarried by the outgoing stream of the solar wind.

Sometimes, due to the orientation of a sunspot when it breaks off, a coronal mass ejection threatens humans on Earth. In 1859, a giant solar explosion known as the Carrington Event snuffed out electric systems across the entire sunward side of the planet. The Carrington event is the most intense geomagnetic storm in recorded history. During the event, the aurora borealis was visible as far south as central Mexico. It was so bright that people reported being able to read a newspaper by its light, even in the middle of the night.

“There was a ghostly splendor on the northern horizon, from which rose fantastic spirals of light, and a rosy glow extended, like a fire-tinged vapor, to the zenith,” wrote the Cincinnati Daily Commercial at the time. The telegraphs threw off sparks and operated themselves, allowing operators to carry on conversations for several hours without their telegraphs being connected to any power source or battery.

Ultimately, stellar and terrestrial winds are possible because gases and liquids obey the laws of fluids in motion. Complex interactions between surface geometry, temperature, humidity, and atmospheric composition influence the Wind patterns on the Earth's surface at a given time.

Besides, Calvin's father might be right.