Fog is a kind of cloud that touches the ground. Fog forms when the air near the ground cools enough to turn its water vapor into liquid water or ice. There are many different types of fog, too. Ice fog forms when the air near the ground is cold enough to turn the water in fog into ice crystals.

When clouds are thin, they let a large portion of the light through and appear white. But like any objects that transmit light, the thicker they are, the less light makes it through. As their thickness increases, the bottoms of clouds look darker but still scatter all colors. We perceive this as gray.

When it’s about to rain, clouds darken because the water vapor is clumping together into raindrops, leaving larger spaces between drops of water. Less light is reflected. The rain cloud appears black or gray. Clouds form when air becomes saturated, or filled, with water vapor.

The cloud looks gray or blue-gray. The sun or moon may shine through an Altostratus cloud, but will appear hazy. An altostratus cloud usually forms ahead of storms with continuous rain or snow. Altocumulus clouds are grayish-white with one part of the cloud darker than the other.

It’s the same with water droplets. Although we can see clouds, if you were to try to touch one your hand would go straight through it. Although we can’t really touch clouds you could walk through one. In fact that’s what fog is: a cloud that’s formed close to the ground instead of high in the sky.

Water is not lighter than air – water does not float. So why don’t clouds fall out of the sky? The two biggest reasons that clouds stay in the sky are 1) small drops, and 2) wind. Because small drops have less mass and more surface area than large drops, they have a harder time pushing the air out of the way.

Clouds do exist, and they do float in the air. The warm, moist air is less dense than the cold air above it, so that warm air rises2. The warm air cools as it comes into contact with the cooler air above. Cold air cannot hold as much moisture as warm air: the vapor has to condense into a liquid.

So, even though typical clouds do contain a lot of water, this water is spread out for miles in the form of tiny water droplets or crystals, which are so small that the effect of gravity on them is negligible. Thus, from our vantage on the ground, clouds seem to float in the sky.

In the cloud, with more water condensing onto other water droplets, the droplets grow. When they get too heavy to stay suspended in the cloud, even with updrafts within the cloud, they fall to Earth as rain.

Condensation is the process of water vapor turning back into liquid water, with the best example being those big, fluffy clouds floating over your head. And when the water droplets in clouds combine, they become heavy enough to form raindrops to rain down onto your head.

As the water vapor rises up in the air, it condenses, or starts to cool down and turns back into a liquid. Then, droplets of water start to stick together as clouds. When enough droplets stick together in the clouds, they become large and heavy and are pulled down towards the earth by the force of gravity.

It is generally safe to eat snow or use it for drinking or for making ice cream, but there are some important exceptions. If the snow is lily-white, you can safely ingest it. But if the snow is colored in any way, you’ll need to stop, examine its color, and understand what it means.

Sleet and snow can still occur in situations in which the surface air temperature is above 45 F when the air aloft cools very rapidly with height but this situation is not common and the precipitation will melt very quickly once it reaches the ground surface.

Air does not hold water very well when the temperature is less than 15 degrees Fahrenheit. So for snow to fall and stay on the ground, the temperature has to be between 15 and the 30s degrees Fahrenheit.

It is true that snow formation relies heavily on the temperature, but not the temperature we feel on the ground. Snow forms when the atmospheric temperature is below freezing; i.e., less than 32°F (0°C). The snow can fall to the ground irrespective of the atmospheric temperature.