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The most direct way to find your question is to search for the name you used when you submitted it (first name, last name or both). If you did not include a name, then you can search using keywords from your question. Of course, since many weather-related terms are common to a lot of the questions we receive, this may turn up a number of others in addition to your own.

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Answer: It's hard to know exactly what you might mean by "things" in this question. If one had to reduce a cloud to two physical components, perhaps you could say clouds are, at their most basic, made up of water and cloud condensation nuclei, as typical clouds in the atmosphere are composed of water droplets or ice crystals, and the tiny particulates of various kinds that can serve as nucleation points upon which the water can condense (as a liquid droplet) or deposit (as an ice crystal) given the correct combination of humidity, temperature and in some cases vertical motion.
Nov. 20, 2009 | Tags: clouds, general meteorology

Answer: Since fog is composed of tiny droplets, or in the case of ice fog tiny frozen crystals, separated by significant amounts of air, it could not and does not form a solid mass in the air, even when the particles themselves are frozen. The point regarding the air being less than freezing, though, is that water needs an appropriate surface upon which to initiate freezing at 32 degrees F, and droplets suspended in air will not typically freeze at that temperature unless they encounter something called an ice nucleus. Even then, with small droplets the ice nuclei are usually most effective at causing the droplets to solidify at temperatures below about 14 degrees F.
Nov. 6, 2009 | Tags: clouds, cold, visibility/fog/dust

Answer: Climate data from the Raleigh-Durham airport seems to indicate your observations are right on target, especially for October. In September, the reported sunrise-to-sunset sky cover averaged 60%, very close to the "normal" value of 59%. However, while the normal number of cloudy days for the month, 11.4, matches the 11 that were observed, when you look at the number of "partly cloudy" days (16, versus a normal of 9.1) and "fair" days (3 compared to a normal of 9.5) you can see that cloud cover appeared to be more prevalent than average. In October, average sky cover was 70% compared to a normal of 49%, and there were 17 cloudy days (normal 11.1), 9 partly cloudy days (normal 7.1) and 5 fair days (well below the normal 12.8). Note that here "fair" indicates 2/10 or less of the sky obscured by opaque clouds, "cloudy" indicates 8/10 or more and "partly cloudy" covers the rest.
Nov. 3, 2009 | Tags: clouds, past weather

Answer: The video and images on the web are a little fuzzy, but it would appear to be a "hole punch" cloud in which the angle of sunlight was such as to make the shallower clouds around the edge of the "hole" appear much brighter than the surroundings. Such clearly-defined round or oval openings in a cloud deck are often associated with penetration by an aircraft, but can occur naturally as well. For more background information in a couple of previous blog posts on our site, just type "holey" into the keyword search box at the top of any web page on our site.
Oct. 21, 2009 | Tags: clouds

Answer: If you are referring to linear or curved lines extending from high-altitude aircraft, the cloud involved is typically composed of a combination of frozen droplets or directly deposited ice crystals that form as water vapor in aircraft exhaust mixes with very cold ambient air, and low concentrations of combustion products such as soot and oxides of carbon, nitrogen and sulfur. These are called condensation trails, or contrails, and they are quite common, existing in a variety of forms depending on the temperature, moisture, stability and wind shear characteristics of the layer of air in which the aircraft is traveling. In especially dry air, they can fail to form or can be so short-lived as to be nearly invisible, while in especially humid air they may be sufficiently persistent to spread, merge and form a layer of cirrus cloud covering much of the sky. The term chemtrails has been applied to trailing clouds by some web site owners who believe materials other than exhaust products are being deliberately released by aircraft in what they purport to be covert and widespread government or corporate projects.
Oct. 12, 2009 | Tags: air quality, clouds

Answer: If your question is "why wasn't it a dark cloud?" then the answer is it is all a matter of perspective and lighting. Even the darkest of storm clouds as seen from underneath or with the sun behind the cloud, will appear white if it is lit by the sun on the side facing you. If the sun is very low or has just set, it may also appear light in color by contrast if there are more distant clouds behind it that are not being lit as brightly and thus appear darker. In either case, if the cloud has the proper characteristics of moisture, height, temperature distribution, and vertical motions, it can produce in-cloud, cloud-to-cloud or cloud-to-ground lightning that may be visible.
Sep. 1, 2009 | Tags: clouds, lightning

Answer: Clouds that are deep enough to produce heavy rain, lightning and hail contain a tremendous amount of water in the form of cloud droplets, rain drops, ice crystals and hail, all of which can scatter, reflect and absorb light. If you happen to be on the opposite side of such a cloud from the sun, it will appear dark due to the lack of light passing though it, and likewise it will become rather dark underneath the storm. On the other had, if you see the same storm cloud, but you are between the sun and the cloud, it will appear bright white due to the light it reflects and scatters back toward you.
Aug. 27, 2009 | Tags: atmospheric optics, clouds, thunderstorms

Answer: The terms have definitions that are based on the fraction of the sky covered by opaque clouds, and are not interchangeable as you've listed them. For example, a clear sky would have 0 eighths (or "oktas") of cloud cover, while mostly sunny would have 1-2 oktas, and partly cloudy would be 3-5. Moving to the other end of the scale, partly sunny is also defined as 3-5 oktas, while mostly cloudy is 6-7 oktas and of course overcast would be 8 oktas. You'll note partly sunny and partly cloudy have the same fraction of coverage. Technically, those two are interchangeable though informally some meteorologists tend to use partly cloudy for the brighter end of that middle range and vice versa.
Aug. 17, 2009 | Tags: clouds, maps & codes

Answer: It has been observed that some hail and/or tornado-producing clouds have a greenish tint to them, but it has not been established that most do, and one can't assume a greenish cloud means a tornado or large hail is imminent, nor can one assume that those things will be absent from a cloud that is not green. The precise reasons for the green apperance remain in some doubt, but one theory is that sufficiently tall and wide cumulonimbus clouds scatter light in such a way as to take on a bluish cast, and then in some cases reddened or deep-yellow light from a low-angle sun (many green cloud observations occur near sunset) combines with the blue to yield the green appearance.
Aug. 10, 2009 | Tags: atmospheric optics, clouds, thunderstorms

Answer: Sometimes when a layer of stable air that is moist but not quite saturated flows across a terrain obstacle like a mountain or a ridge line, the air is forced upward. If this cools the lifted air sufficiently, a smoothed layer of cloud may form on the upwind side and then rapidly dissipate again where the air subsides farther downwind of the obstacle. These orographically-induced phenomena are a type of "lenticular" cloud, and have on occasion led to UFO reports from observers unfamiliar with them!
Jun. 23, 2009 | Tags: clouds, cool sites