What makes water condense

Even though clouds are absent in a crystal clear blue sky, water is still present in the form of water vapor and droplets which are too small to be seen. Depending on weather conditions, water molecules will combine with tiny particles of dust, salt, and smoke in the air to form cloud droplets, which combine and grow and develop into clouds, a form of water we can see.

Cloud droplets can vary greatly in size, from 10 microns millionths of a meter to 1 millimeter mm , and even as large as 5 mm. This process occurs higher in the sky where the air is cooler and more condensation occurs relative to evaporation. As water droplets combine also known as coalescence with each other, and grow in size, clouds not only develop, but precipitation may also occur.

Precipitation is essentially water in its liquid or solid form falling from the base of a cloud. This seems to happen too often during picnics or when large groups of people gather at swimming pools. This picture shows cumulonimbus clouds over Africa photographed from the International Space Station. Tap the picture to get an in-depth explanation.

The clouds formed by condensation are an intricate and critical component of Earth's environment. Clouds regulate the flow of radiant energy into and out of Earth's climate system. They influence the Earth's climate by reflecting incoming solar radiation heat back to space and outgoing radiation terrestrial from the Earth's surface. Often at night, clouds act as a "blanket," keeping a portion of the day's heat next to the surface. Changing cloud patterns modify the Earth's energy balance, and, in turn, temperatures on the Earth's surface.

As we said, clouds form in the atmosphere because air containing water vapor rises and cools. The key to this process is that air near the Earth's surface is warmed by solar radiation. But, do you know why the atmosphere cools above the Earth's surface?

Generally, air pressure, is the reason. The pressure weight , called barometric pressure, that results is a consequence of the density of the air above. At higher altitudes, there is less air above, and, thus, less air pressure pressing down. The barometric pressure is lower, and lower barometric pressure is associated with fewer molecules per unit volume.

Therefore, the air at higher altitudes is less dense. As the total heat content of a system is directly related to the amount of matter present, it is cooler at higher elevation This means cooler air. On California's Marin Headlands, facing away from the Golden Gate Bridge, the August heat hits the cool air from the Ocean, creating a very thick fog that tends to sit low on the ground.

Condensation also occurs at ground level, as this picture of a cloud bank in California shows. The difference between fog and clouds which form above the Earth's surface is that rising air is not required to form fog.

Fog develops when air having a relatively high humidity comes in contact with a colder surface, often the Earth's surface, and cools to the dew point. Additional cooling leads to condensation and the growth of low-level clouds. Fog that develops when warmer air moves over a colder surface is known as advective fog. Another form of fog, known as radiative fog, develops at night when surface temperatures cool. If the air is still, the fog layer does not readily mix with the air above it, which encourages the development of shallow ground fog.

You probably see condensation right at home every day. If you wear glasses and go from a cold, air-conditioned room to outside on a humid day, the lenses fog up as small water droplets coat the surface via condensation. People buy coasters to keep condensed water from dripping off their chilled drink glass onto their coffee tables. Condensation is responsible for the water covering the inside of a window on a cold day unless you are lucky enough to have double-paned windows that keep the inside pane relatively warm and for the moisture on the inside of car windows, especially after people have been exhaling moist air.

All of these are examples of water leaving the vapor state in the warm air and condensing into liquid as it is cools. Air, even "clear air," contains water molecules. Clouds exist in the atmosphere because of rising air. As air rises and cools the water in it can "condense out", forming clouds. Since clouds drift over the landscape, they are one of the ways that water moves geographically around the globe in the water cycle.

A common myth is that clouds form because cooler air can hold less water than warmer air—but this is not true. As Alistair Fraser explains in his web page " Bad Meteorology ": "What appears to be cloud-free air virtually always contains sub microscopic drops, but as evaporation exceeds condensation, the drops do not survive long after an initial chance clumping of molecules. As air is cooled, the evaporation rate decreases more rapidly than does the condensation rate with the result that there comes a temperature the dew point temperature where the evaporation is less than the condensation and a droplet can grow into a cloud drop.

When the temperature drops below the dew-point temperature, there is a net condensation and a cloud forms," accessed on Sep. You've seen the cloud-like trails that high-flying airplanes leave behind and you probably know they are called contrails.

It is the reverse of evaporation , where liquid water becomes a vapor. Condensation happens one of two ways: Either the air is cooled to its dew point or it becomes so saturate d with water vapor that it cannot hold any more water. Dew Point Dew point is the temperature at which condensation happens. Dew is simply condensed water in the atmosphere.

Air temperatures can reach or fall below the dew point naturally, as they often do at night. Thats why lawns, cars, and houses are often coated with water droplets in the morning. Condensation can also produce water droplets on the outside of soda cans or glasses of cold water.

When warm air hits the cold surface, it reaches its dew point and condenses. This leaves droplets of water on the glass or can. When a pocket of air becomes full of water vapor, clouds form. The point at which condensation starts can be easily viewed in cumulus clouds, which have flat bottoms. Those flat bottoms are where vapor begins to condense into water droplets. Saturation Clouds are simply masses of water droplets in the atmosphere.

Molecule s in water vapor are far apart from one another. As more water vapor collects in clouds, they can become saturated with water vapor. Saturated clouds cannot hold any more water vapor. When clouds are saturated with water vapor, the density , or closeness, of the molecules increases. The vapor condenses and becomes rain. Cold air holds less water vapor than warm air. This is why warm climates are often more humid than cold ones: Water vapor remains in the air instead of condensing into rain.

Cold climates are more likely to have rain, because water vapor condenses more easily there. Droplets on your can of soda. The cold surface of the can causes moisture in the warm exterior air to condense on the outside of the can.

A foggy windshield. The air in your car contains moisture, and more is added from the breath and bodies of passengers. With enough moisture, and a cool enough windshield, the moisture condenses as droplets that fog your window. A foggy mirror.

The same thing happens in your bathroom when shower moisture condenses on a cool mirror. Foggy breath. Can you see your breath? Then it's cold outside; cold enough to condense moisture into larger droplets.

This is an example of condensation occurring without a surface to collect the drops. The clouds in the sky are another example of condensation without a surface. What Does the Condensation Process Require? The Effects of Temperature Inversion.