What is Cloud: Definition and 254 Discussions

In meteorology, a cloud is an aerosol consisting of a visible mass of minute liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may compose the droplets and crystals. On Earth, clouds are formed as a result of saturation of the air when it is cooled to its dew point, or when it gains sufficient moisture (usually in the form of water vapor) from an adjacent source to raise the dew point to the ambient temperature.
They are seen in the Earth's homosphere, which includes the troposphere, stratosphere, and mesosphere. Nephology is the science of clouds, which is undertaken in the cloud physics branch of meteorology. There are two methods of naming clouds in their respective layers of the homosphere, Latin and common.
Genus types in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names due to the universal adoption of Luke Howard's nomenclature that was formally proposed in 1802. It became the basis of a modern international system that divides clouds into five physical forms which can be further divided or classified into altitude levels to derive ten basic genera. The main representative cloud types for each of these forms are stratus, cirrus, stratocumulus, cumulus, and cumulonimbus. Low-level clouds do not have any altitude-related prefixes. However mid-level stratiform and stratocumuliform types are given the prefix alto- while high-level variants of these same two forms carry the prefix cirro-. Genus types with sufficient vertical extent to occupy more than one level do not carry any altitude related prefixes. They are classified formally as low- or mid-level depending on the altitude at which each initially forms, and are also more informally characterized as multi-level or vertical. Most of the ten genera derived by this method of classification can be subdivided into species and further subdivided into varieties. Very low stratiform clouds that extend down to the Earth's surface are given the common names fog and mist, but have no Latin names.
In the stratosphere and mesosphere, clouds have common names for their main types. They may have the appearance of stratiform veils or sheets, cirriform wisps, or stratocumuliform bands or ripples. They are seen infrequently, mostly in the polar regions of Earth. Clouds have been observed in the atmospheres of other planets and moons in the Solar System and beyond. However, due to their different temperature characteristics, they are often composed of other substances such as methane, ammonia, and sulfuric acid, as well as water.
Tropospheric clouds can have a direct effect on climate change on Earth. They may reflect incoming rays from the sun which can contribute to a cooling effect where and when these clouds occur, or trap longer wave radiation that reflects back up from the Earth's surface which can cause a warming effect. The altitude, form, and thickness of the clouds are the main factors that affect the local heating or cooling of Earth and the atmosphere. Clouds that form above the troposphere are too scarce and too thin to have any influence on climate change. Clouds are the main uncertainty in climate sensitivity.

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  1. sophiecentaur

    I Oort Cloud and Kuiper Belt: differences

    When I read about formation of solar systems it seems reasonable to me that most of the material would end up lying in a plane because the number of collisions and interactions would be least and the most stable situation in a common orbital plane in the long run. (Is this a far too simplistic...
  2. kamui1

    Solving for degeneracy electron cloud temperature

    When I try P_rel_e = P_ideal I couldn't get a single number that is close to the given T_Max. It might be that I used the wrong equations but I am not sure. Can anyone give me some guidence on this question?
  3. shivajikobardan

    Comp Sci Help me choose Cloud technology for small business-:

    IMO IaaS would be the right choice as most of the things you can change yourself rather than depending on cloud.. What do you think?
  4. Tristan_Ruel

    I Help getting my Cloud Chamber to work please

    Hello! I'm currently building a cloud chamber, my end goal is to make it powered by Peltier chips but that won't happen until I can make it work with dry ice. I've been able to achieve a supersaturated layer of isopropyl alcohol in the chamber, however, even with very radioactive uranite...
  5. D

    Other How much does a Cloud Computing position earn in Austria?

    How much does a Cloud Computing position earn in Austria in general? I need this answer for an interview in order to negotiate with the interviewers. I hold a PhD degree in Physics but with no experience in the field.
  6. rudransh verma

    Understanding Fog Formation and Dew Point from Wikipedia

    I read in Wikipedia that fog is formed when the water vapor in air is condensed to form liquid water that are suspended around condensation nuclei. Fog or clouds don't move from some place but appear in places through condensation. Now there is something about dew point which has to do with the...
  7. P

    A Molecular cloud collapsing and fragmentation

    Good morning, I read on the internet that a molecular cloud contains denser part, I also read that a molecular cloud start to collapse according the Jeans law If it's the full cloud collapsing what is happening to these denser parts ? and after collapsing how the fragmentation occurs ? In fact...
  8. edusmartin

    B Cloud Chambers - I to know what particle this is

    Hi, my son is fan of the Quantum Physics and we developed a cloud chamber. I'm attaching an image of particle sequence and I will like to find some help to know witch particle is. I will appreciate any help on it. Thanks
  9. xpell

    How large can a cloud cover be?

    Hi! I was watching satellite pics of the Earth and I noticed that continuous cover clouds can be really large. So... I felt curious and my question is obvious: Please, does anybody know how large can a cover cloud be on planet Earth, or at least a few of the largest measured ones? (Not...
  10. D

    Supermassive black hole in the Large Magellanic Cloud?

    Ok, I know, it's science fiction, you can make anything work if you really want it to. I'm planning out a sci-fi story which I wanted to try and keep as grounded as possible in believable scientific concepts. For context, the basic premise is: humanity detects a wormhole on the outer edge of the...
  11. SimranPaudel

    Engineering How Do You Calculate the E-field in an Electron Cloud Using Gauss's Theorem?

    I tried to use the formula for electric field intensity but I feel like something is missing.
  12. H

    I Oort Cloud Dynamics: Interaction, Composition, Hazards

    1. Assuming the Oort Cloud of the Solar System stretches 'almost' to our nearest Star neighbour, how would it interact with that Star's 'Oort Cloud'? I imagine objects constantly colliding between the two systems perhaps causing them to leave the cloud. 2. Does the Oort cloud form a ring of...
  13. DaveC426913

    Modern file backup options: cloud? / HD?

    I thought I had a long-term backup of my important stuff when I bought a 1Tb Seagate External Drive. It died and took years of projects and memories with it. Running Win10 on a laptop. I think there are three options: Another (better) external drive Some newfangled solid-state external drive...
  14. person123

    I Computing the Density of a Point Cloud

    Hi. For some background, I am running molecular dynamics simulations of silica fracture in LAMMPS. Each point represents the location of a broken bond. I would like to find regions where many bonds are breaking, which I speculate would be locations of crack formation. These computations are...
  15. A

    I What causes Kuiper/Ort cloud objects to become comets?

    I was reading about comets and know they come from the Oort or Kuiper Cloud. However, being composed of materials, comets that continually orbit the sun shed the substance that makes them up and, from what I've read, will only thus last for thousands, maybe tens of thousands of years. I know...
  16. George Keeling

    I Questions about spaghettification and gas cloud G2

    I did an exercise about beacons falling radially into black holes from Carroll's book and got a formula for the proper velocity$$ \frac{dr}{d\tau}=-\sqrt{\frac{R_S}{r_\ast}}\sqrt{\frac{r_\ast-r}{r}} $$It's in natural units (##c=1)##, ##r_\ast## is where the beacon is dropped from and ##R_s=2GM##...
  17. Merlin3189

    Cloud chamber - electron tracks? - solved

    Following a thread on building a cloud chamber I searched some other sites and encountered some eg. diagrams of electron tracks which puzzled me. I searched for actual photos and found some very irregular tracks ascribed to electrons, but nothing like these. I can't see how they could arise...
  18. N

    Misc. Problem with my cloud chamber -- have a mist but no tracks

    Hi, For a few weeks I'm trying to build a Peltier based cloud chamber. I use a stack of 3 Peltier (from the bottom, a tec1-12710 12v, tec1-12710 5v, tec1-12709 5v and on top a 60mmx60x2.5 copper plate). I mesured -37° celcius on top of the last Peltier ans -27° on the copper plate. I also have...
  19. T

    What is the difference between Grid and Cloud Computing?

    Good Morning I have googled this issue (the difference between Grid and Cloud computing, as per subject line), but I find many of the definitions overlap each other and leave a lot of ambiguity. A lot of the examples focus on manipulation of data (versus independent processes). But BEFORE I...
  20. E

    Rocket moving through a cloud of dust, variable mass problem

    The first way to solve this is to just say, by conservation of momentum, that M_{0}v_{0}=(M_{0}+Apx)\frac{v_0}{2} where Apx is the mass of dust the rocket comes into contact with in a distance x. For the second method, by considering the change of momentum of the dust in 1 second, we know the...
  21. C

    Details of the electron cloud in a magnetron: density and size?

    In a standard kitchen-microwave magnetron, like all magnetrons, a cloud of electrons forms which whizzes around and generates GHz electric currents in an outer ring electrode. For such a standard kitchen appliance, 800W made with ferrite magnets, what is the typical volume and density of the...
  22. F

    B Does the Density of a Portable Cloud in a Bottle Depend on Pressure?

    I met an experiment on youtube, where a man creates a cloud in a bottle. Do density of such cloud depends on pressure inside the bottle before opening? If yes, how?Here is a link!
  23. hagopbul

    Cloud chamber approach to stopping hurricanes

    mod note: positively no politics will be allowed Hello All: The current hot topic on the news is using nuclear weapons against hurricanes . But couldn't we use other approaches ,using some nuclear reactors mounted in a plane or balloon that emit calculated levels of radiation in the center of...
  24. S

    Mathematica Wolfram Cloud Notebook : Indenting Code

    I tried adding spaces manually to indent a multiline code block in a notebook on Wolfram Cloud (www.wolframcloud.com). It throws the "Set: Tag Times" error. How can I indent code lines (preferably manually, but auto will also be fine).
  25. Parzeevahl

    Pressure and Volume of a Neutral Hydrogen Cloud

    Here's how I approached it. We know the total mass of the cloud, it is given. Let's call it 'M'. We can also find out the mass of a single hydrogen atom from its atomic weight. Let's call this 'm'. Then N = M / m is the total number of hydrogen atoms in the cloud. The temperature (T) is given...
  26. G

    B Cloud Cities on Venus: Viability & Feasibility

    There are plans for almost everything. https://www.space.com/29140-venus-airship-cloud-cities-incredible-technology.html Like build floating cities on Venus in the far future, since gravity is Earth like at there, and the upper atmosphere isn't so harsh. I would like to hear your opinions...
  27. jim mcnamara

    A 'what if' model of cloud cover and increased warming

    Popular reporting: https://www.washingtonpost.com/climate-environment/2019/02/25/very-high-carbon-dioxide-could-suppress-cooling-clouds-climate-change-model-warns/?utm_term=.d40e5e576254 Article in Nature Geoscience: https://www.nature.com/articles/s41561-019-0310-1 (I can see the article, may...
  28. HotFurnace

    B Effects of Cooling and Heating in a Cloud Chamber

    Good day everybody! As we have already known the structure and operation of the cloud chamber, can someone explain to me why the cooling is done at the bottom of the chamber and the heating at the top, but not vise versa?? How this affect the function of the cloud chamber?
  29. N

    Homemade cloud chamber not working

    I am a HS teacher working with a class of seniors on building a cloud bubble chamber. I have mostly used this article to guide us, but the students have also done research and have found many articles and videos as well. We are using a small plastic fish tank with felt super-glued to the...
  30. B

    I Atmospheric Lapse Rate (calculating the altitude of cloud formation)

    This is probably more of a p-chem question but I figure you guys are smart enough to answer this. FREEZING LEVEL CALCULATION: Per FAA "A standard temperature lapse rate is when the temperature decreases at the rate of approximately 3.5 °F or 2 °C per thousand feet up to 36,000 feet" Easy...
  31. nomadreid

    Storage of material from CD's and DVD's: cloud?

    The question is from a friend of mine who is computer-incompetent; I am only computer literate on a daily-citizen level (can follow instructions from software but never learned to read or write code). Although I cannot sit down at his computer with him (he lives in the US, about 11000 km from...
  32. J

    I Why hasn't the Oort cloud converged to a disk shape?

    The Oort cloud is often drawn as a sphere. Everything in it orbits the sun in circles or ellipses. Since the shape is not a disk, collisions are expected. Why hasn't the Oort cloud converged to the more stable, collision-free, disk shape?
  33. I

    I Why Is the Velocity of an Oort Cloud Object Approximately Zero?

    I read that the the energy of an Oort cloud object is approximately zero, as in the potential energy plus the kinetic energy is equal to zero. I was also told that the radius was approximately infinite and the velocity is approximately zero. I understand why the radius is said to be infinite...
  34. dRic2

    Cloud storage vs physical memory

    Hi, I need more memory (not to much though... 50GB should be fine for now), but I don't know whether to buy an external hard drive or try cloud storage. I'm pretty dumb when it comes to computers and related stuff so I'd like to hear some suggestions. Thanks Ric
  35. S

    Cloud cropping/plureite sensors

    I saw a video on facebook recently of some sort of devices making circles in the clouds, revealing the blue sky above. I thought at first this was fake but apparently not. Someone provided the explanation using the above terms...cloud cropping and plureite sensors, but I can no longer find the...
  36. jim mcnamara

    B Sholz's star entered the Oort cloud ~70kya

    https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.html https://academic.oup.com/mnrasl/article-abstract/476/1/L1/4840245?redirectedFrom=fulltext (abstract) R. de la Fuentes, S. J Aarseth Based on an earlier paper (E. Mamajek 2015) that indicated Sholz's star passed very...
  37. physea

    Cloud Altitude: Understanding the Height Range of Clouds

    << Mentor Note -- poster has been reminded to do some reading on their own before asking simple questions at the PF >> Are clouds mostly in a specific height range from sea level? If yes, what is that height?
  38. E

    Rocket momentum through a cloud of particles

    Homework Statement A cylindrical rocket of diameter 2R and mass M is coasting through empty space with speed v0 when it encounters an interstellar cloud. The number density of particles in the cloud is N particles/m^3. Each particle has mass m << M, and they are initially at rest. Assume each...
  39. C

    B How Can Astronomy Even Occur? (Oort Cloud)

    I watched a show on TV about the Oort cloud, that featured a visual. I think it mentioned something like several trillions with a t objects surrounding the Sun outside the solar system. And the image showed just that, a cloud so dense and thick you couldn't see the sun. Combine that with all the...
  40. BillTre

    Testing Cloud Seeding: Science Magazine News Report

    Here is a Science magazine News Report on some clever (to me anyway) testing of seeding clouds with Silver Iodine vs. induced snow formation.
  41. Physics Dad

    Astrophysics Problem - Effects of cloud on flux density

    Hi, I am attempting the following question: 1. Homework Statement If the extinction in the infrared K-band (filter central wavelength = 2.13 micrometres) is 10 times less than it is in the optical V-band (filter central wavelength = 550 nanometres), what affect would a cloud of Av = 3 have on...
  42. FallenApple

    A Detecting a Torus in a data cloud

    Would the following method work? I could uniformly distribute points into the data cloud. Of the "darts" that I threw in, create edges between all points with a metric value under a certain amount. The nodes in the resulting graph that have more neighbors would indicate greater density. I could...
  43. D

    B Understanding the probability cloud?

    I understand that the concept of a atom resembling a solar system is disregarded as being untrue because this is based on the Bohr model which doesn't represent how an electron would actually appear in its probability cloud. However, would it be possible that if there were an observer on the...
  44. EEristavi

    B Condensation & Clouds: Understanding Water's Transformation

    I understand that condensation occurs when water (in gas form) looses energy and becomes liquid. What I don't understand why some surface is needed to form a liquid water
  45. shihab-kol

    Rainy Day: Black Clouds and Light

    During a rainy day the clouds appear black but not so normally (in good climatic conditions) I think its something to do with light so I posted this query . If its not, sorry.
  46. D

    Shockwave of mushroom cloud rising at supersonic speed

    I'm modelling the Hiroshima nuclear explosion on a real time real scale physics simulator. My initial simulations based on data accumulated from wikipedia such as temperature of the fireball the radius of it and using air pressure and air density data based on the detonation height of 600m has...
  47. BillTre

    Cloud Atlas (not the movie) Gets an Update

    Newly described clouds (also here) have been added to the International Cloud Atlas. I have always found clouds kind of fascinating, especially when viewed from airplanes. Didn't even know there was a cloud atlas.
  48. Jr_Particle_Hunters

    B Beta particle penetration in our cloud chamber?

    Hello. We are elementary school kids who built a cloud chamber for our science project to test out the effectiveness of different shields against background radiation. We are not sure about something involving beta-particles. Can you help us please? We know low-energy beta particles cannot...
  49. Gjmdp

    B How can I make an original cloud chamber?

    I'm trying to do a cloud chamber, but I think they are all too common and simple. It's just a box. I've thought about doing in a bottle, but it is just too weird, and is not original. Any other ideas or hints?
  50. doggonemess

    I My cloud chamber didn't make any tracks....

    Greetings all, I finally made a cloud chamber using an old aquarium and dry ice. Now, I got the expected result to happen, with a fine mist falling from the top like snow, but didn't see a single particle track. Any ideas why this might be? I have some guesses, but wanted someone with...