How heavy is a cloud floating in the sky? How is weight affected?

The cloud is not even as big as the football field on the ground, but it is also small because of its close distance, with a total weight of tens of thousands of tons. Clouds are actually composed of many small ice crystals and water droplets, and their quality is related to coverage and thickness.

This problem has something to do with people's eyesight, the height of clouds and many other factors. The human eye is actually a system of optical refraction and energy conversion. In this system, the external light is refracted by cornea and lens and converged near the fovea of retina, and then the optical signal is converted into electrochemical signal by visual cells. The photorefractive structure such as cornea can condense light, so everything seen by human visual system is near big and far small.

The height of clouds from the ground is usually about 2000 meters. In some special geographical environments, due to the blocking of airflow by mountains, the height of clouds can rise to four or five kilometers. On the one hand, with the increase of altitude, water vapor in the atmosphere is more likely to condense into water droplets and ice crystals. On the other hand, such a high cloud is much smaller to people on the ground. Maybe a cloud covering several square kilometers looks as big as a football field on the ground.

Clouds are actually the result of water vapor refracting light. Under normal circumstances, when we observe a glass of water, we will find that the water becomes brighter, which is actually only the result of water refracting light. Water itself has no color, but the difference in refractive index between water and air enables us to see a clear water-air interface. The same is true of clouds, which are small water vapor droplets in the sky, but because of their refraction of light, visible light is dispersed, so we can see the obvious boundary between clouds and the general atmosphere. Usually, when the clouds are thin, there is not only scattered light, but also directly transmitted light, so the clouds look white and loose, but sometimes the clouds look thick and black because they absorb more light.

The visual effect of near big and far small makes us underestimate the size of clouds, and the transmission and refraction of light will have similar effects. Generally speaking, the area covered by clouds is usually large, but during the day, although there are many clouds, the sky is still bright because there is a lot of transmitted and scattered light. When the clouds are overcast, the thickness and height of clouds are usually high, and the dense distribution of clouds leads to less transmitted light. When the height is high, the air is cold, which is more conducive to the combination of water and dust and other condensation nuclei into raindrops. Finally, the gravity of the water droplets counteracts the lift of the updraft, and the water droplets in the cloud become raindrops and fall to the ground.

In the strong convective weather in summer, a cloud looks small, but it covers a considerable area. At the same time, due to the upward airflow, clouds tend to surge to higher heights. This kind of cloud is often called cumulonimbus cloud, which is the phenomenon of water vapor condensation when the lower temperature of the cloud flows to the upper air. Small-looking clouds have accumulated hundreds of tons of water. Sometimes, in a wide range of strong convective weather, clouds are always condensed, and the final precipitation can be hundreds of millions.