The Real Reason Why Clouds Move

Clouds come in many shapes and sizes, from little wisps on the horizon to towering black masses that block out the sun. These giant puffy pillows of water vapor can be quite the traveler, with some crossing oceans and mountain ranges. When a cloud streaks along the sky, what exactly is pulling them along? It has nothing to do with the rotation of the Earth or how close the clouds are to the Equator, as the movement of clouds is dictated by wind (via UCL).

Clouds can move even when conditions on the ground don't feel windy at all. This is because clouds exist on nearly all layers of the atmosphere, from down near where some of our taller buildings can reach to miles in the air where commercial jetliners fly. Generally, the higher you go up in the atmosphere, the stronger wind conditions get, so loftier clouds tend to be speedier clouds, even when those gazing up at them on the ground feel the air to be completely still.

Wind is caused by pockets of hot air moving to colder areas, and they sometimes form fast currents called jet streams that can carry clouds across continents and oceans, bringing warmer temperatures along with them (via UCL). A cloud caught in a jet stream would be obvious to anyone who happened to witness it, but sometimes clouds can be moving while appearing stationary.

According to NIWA, lenticular clouds, which form near hills, seem to resist even the strongest of winds, but this is actually an illusion. Droplets on one end of the cloud are being pushed back, but since the wind is pushing the air towards it, new droplets immediately replace the ones that have been moved. This occurs at both ends of the clouds, meaning it constantly replaces itself while appearing to sit calmly in the face of heavy wind. The movement of clouds can be a fascinating process that can bring the salvation of rain, the destruction of storms, or just a neat optical illusion where a very busy process can seem like nothing is happening at all.