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. Maybe you didn't know they were called that because they are actually condensation trails and, in fact, are not much different than natural clouds. If the exhaust from the airplane contains water vapor, and if the air is very cold which it often is at high altitudes , then the water vapor in the exhaust will condense out into what is essentially a cirrus cloud.
As a matter of fact, sailors have known for some time to look specifically at the patterns and persistence of jet contrails for weather forecasting. On days where the contrails disappear quickly or don't even form, they can expect continuing good weather, while on days where they persist, a change in the weather pattern may be expected.
Contrails are a concern in climate studies as increased jet traffic may result in an increase in cloud cover. Several scientific studies are being conducted with respect to contrail formation and their impact on climates.
Cirrus clouds affect Earth's climate by reflecting incoming sunlight and inhibiting heat loss from the surface of the planet. It has been estimated that in certain heavy air-traffic corridors, cloud cover has increased by as much as 20 percent.
Source: National Weather Service: What is a contrail and how does it form? Condensation causes clouds. The Oxford English Dictionary defines a cloud as "a visible mass of condensed watery vapor floating in the air at some considerable height above the general surface of the ground. And they do "fall" on you, sometimes, when the fog rolls in. According to columnist Cecil Adams, "a modest-size cloud, one kilometer in diameter and meters thick, has a mass equivalent to one B jumbo jet.
If you compressed that cloud into a trash bag, well, in that case, you would not want to be standing below it. Even though a cloud weighs tons, it doesn't fall on you because the rising air responsible for its formation keeps the cloud floating in the air. The air below the cloud is denser than the cloud, thus the cloud floats on top of the denser air nearer the land surface.
Source: Gleick, P. In Encyclopedia of Climate and Weather, ed. Unlike hot air, colder air is less able to hold water vapor, which forces the gaseous water around cool objects to condense. Temperatures reach the dew point most usually at night — and especially during summer when warm days are followed by cool nights. This is why you might see water droplets outside your windows, on your lawn, or on your car in the morning.
This type of condensation happens when humidity levels are high and when the exterior surface temperature falls below the dew point. As Carroll told Live Science: "Condensation can form on windows, and other surfaces, at any time of the year. In the winter, condensation often builds up on the windows because the outside air temperature is much lower than indoors.
Windows can have very little resistance to heat flow, so even the interior side of most windows will be closer to the outdoor temperature than the indoor temperature.
During the summer, the outside of a window can be cool from the air conditioning inside, so water vapor can condense on the exterior side of windows on a hot, humid day. But don't worry — dew on the exterior of your windows doesn't mean they are faulty or malfunctioning. If you have noticed droplets on your glass, head to our feature answering; is condensation on windows bad? If you're plagued with condensation between your window panes, it might be a sign of damage to the window components and is most often caused by the failure of the seal between those panes.
As well as looking aesthetically unappealing, it can cause wider issues — like mold — if it's not dealt with. As Carroll explained: "The failed gasket will allow the dry and inert gas filling the space between panes to escape. This will be replaced naturally by air containing moisture from either inside or outside the home. If the temperature of an object e. This dew point varies according to the amount of water in the atmosphere and air temperature known as relative humidity. In humid conditions, condensation occurs at higher temperatures.
In cold conditions, condensation occurs despite relatively low humidity. With regard to windows and doors, it is the difference in temperature between the environment, be it internal or external, and the glass, that causes condensation to form. The air surrounding us in our homes always contains water vapour, which is invisible. A typical example is the steam cloud from a kettle, which rapidly becomes invisible — it has in fact been absorbed into the atmosphere.
The warmer the air, the more water vapour it can hold — but there is a limit to the amount it can hold for a given temperature. When saturated air comes into contact with a surface that is at a lower temperature than itself, the air is chilled at the point of contact and sheds its surplus water vapour on that surface — initially in the form of a mist and, if excessive, eventually in the form of droplets of moisture. An example of this is when a person breathes onto a mirror: condensation occurs because the exhaled air is saturated and its temperature is higher than that of the mirror which is at room temperature.
This is produced by normal living activities such as washing, cooking, bathing, etc.
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