The wind can move heavy objects because it exerts a force on them due to its speed and pressure. These forces can be sufficient to move heavy objects over short distances.
Atmospheric pressure changes with temperature: warm air is light, it rises, creating a low-pressure area near the ground. Conversely, denser cold air descends, leading to a high-pressure area at ground level. You can think of it like the warm air in a balloon: the balloon rises when the air inside is warmer because it is less dense, and it descends when it cools down. These pressure differences push the air to circulate; this movement of air is what you call wind. The greater the temperature differences between different regions, the larger the pressure differences become, and the stronger the winds can get.
The force exerted by the wind on an object increases dramatically as its speed starts to rise a bit. In fact, if the wind speed doubles, the force applied to an object is multiplied by about four. This is because the pressure of the wind is proportional to the square of its speed. So, there's no need for extraordinarily fast winds for them to start moving heavy objects, like garden furniture, panels, or even uprooted trees: even a small increase in speed quickly multiplies the energy available to move heavy things. That's why seemingly moderate winds can already cause significant damage.
The exposed surface to the wind is essential: a lightweight but wide and flat piece of furniture will catch more wind than a compact and narrow object. The shape also plays a significant role: objects with hollow parts or right angles strongly promote turbulence, increasing their wind resistance. The weight is obviously crucial, but also, and above all, the way it is distributed: a heavy object with a high center of gravity can easily tip or roll over. Finally, the surface texture is important: a smooth material allows air to flow with fewer obstacles, unlike a rough or uneven surface that better captures the wind.
Gusts are sudden increases in wind speed that violently push an object, creating a momentary and intense force. Even a heavy object, if subjected to a strong enough gust and having a large surface area exposed to the wind, can start to tip or slide. For their part, turbulence, with its unpredictable chaotic movements, can create a leverage effect, destabilizing or slightly lifting even imposing objects, thus allowing the wind to push them more easily. These short but powerful phenomena explain how a large garbage bin, a caravan, or an entire roof can sometimes be moved or overturned, even by moderate winds.
Tornadoes, hurricanes, and other violent storms generate extreme winds capable of moving very heavy objects. In these cases, winds can exceed 300 km/h, a speed more than sufficient to lift cars or tear entire houses apart. The key is mainly the enormous difference in atmospheric pressure that accompanies these phenomena and amplifies their force. A tornado acts almost like a gigantic vacuum cleaner: any object within reach can quickly take off. For hurricanes, it is also their large size and longer duration that allow them to cause massive damage over great distances. Moreover, the faster or more turbulent the wind, the more it generates powerful air movements that rush underneath even massive objects, making them abruptly less stable.
The strongest winds ever recorded on Earth reached 484 km/h during a tornado in Oklahoma in 1999, a speed capable of lifting vehicles and destroying particularly heavy structures.
In some desert regions, rocks weighing several dozen kilograms seem to mysteriously move over time due to the combined action of strong winds and the slippery ground after rare rains.
When the wind doubles its speed, the force exerted on an object is multiplied by four: this is why even slight increases in speed can have significant consequences on exposed objects.
In 1931, a tornado in the United States was able to lift and move an 83-ton train, thereby demonstrating the extraordinary power of the wind in extreme conditions.
It is advisable to store lightweight objects indoors when a weather alert is issued. Otherwise, use ropes, straps, or heavy weights to secure them, reduce their surface area exposed to the wind by laying them down or disassembling them, and, if possible, place them in a sheltered location away from the prevailing wind.
Gusts are sudden and violent accelerations of the wind. Due to their unpredictable nature, they exert a significant force on objects abruptly, catching them off guard and increasing the risk of movement or damage compared to a steady wind.
Generally, starting at around 70 km/h, some moderately heavy objects may begin to move depending on their shape and size. However, heavy or less exposed objects often require winds exceeding 90 to 100 km/h to be clearly displaced.
The extreme wind speeds at the heart of tornadoes can exceed 300 km/h, creating a significant pressure difference around and beneath objects. This ability to lift and project heavy objects comes from the combination of immense force due to speed and violent turbulence.
Objects with a large surface area relative to their mass, such as trash bins, umbrellas, lightweight garden furniture, trampolines, or construction panels, are particularly vulnerable to strong winds and gusts.
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