Precipitation Definition and 10 Discussions

In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzling, rain, sleet, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers.Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain. This process is typically active when freezing rain occurs. A stationary front is often present near the area of freezing rain and serves as the focus for forcing and rising air. Provided there is necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely nimbostratus and cumulonimbus if significant precipitation is involved. Eventually, the cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where relatively warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be locally heavy. Thundersnow is possible within a cyclone's comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation occurs within the tropics and is caused by convection. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah regions.
Precipitation is a major component of the water cycle, and is responsible for depositing fresh water on the planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year: 398,000 cubic kilometres (95,000 cu mi) over oceans and 107,000 cubic kilometres (26,000 cu mi) over land. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in), but over land it is only 715 millimetres (28.1 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes.
Precipitation may occur on other celestial bodies. Saturn's largest satellite, Titan, hosts methane precipitation as a slow-falling drizzle, which has been observed as Rain puddles at its equator and polar regions.

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  1. SanaiBongchul

    Green's reciprocity theorem about current density and magnetic field

    I have to prove three equations above. For first two equations, I've been thought and made reasonable answer by using a definition of the electricfield. However, for third, I can't use a definition of a magnetic field due to the cross product Like J_2 X J_1 X (r_2 - r_1). I think three of 'em...
  2. Quentin_alex

    Co precipitation of ceria-zirconia-lanthana catalyst support

    My question concerns the resultant particles of a co precipitation reaction. What effects occur when you accelerate/decelerate a co precipitation reaction? What are optimal conditions (speed, etc.) for this process? I am interested primarily in the effects on the resultant powder. Thank you.
  3. D

    Water molecules effect on Hydrogen bonds in precipitation

    Cheers everyone. Can the amount of water molecules added to a solution impact the formation of a salt with its ions mainly bonded through hydrogen bonds with electrostatic like behaviour? Let me give Some background to the question first: I am studying the precipitation of Phosphorous(P) as...
  4. B

    Predicting precipitates in a solution

    Let's say we have a solution supersaturated with several species of ions, and there are a few potential precipitates predicted to be formed that all have one contain one species in common (therefore they are competing for that common ionic species). How can we predict which species will...
  5. B

    Help please with this precipitation exercise

    Knowing Ks=6⋅10−38 for Fe(OH)3 in neutral solutions, calculate the minimum pH of an acidic solution in order to completely dissolve 10 mg of Fe(OH)3. Data: Volume = 0.1 L. I set out the equation for the equilibrium constant. having first calculated the concentration or iron ions (9.35899*10-4...
  6. TheSodesa

    Precipitation of lead hydroxide in the presence of EDTA

    Homework Statement 1. The question EthyleneDiamineTetra-acetate(##EDTA^{4-}##) is used in chemical analysis as a complex-former. ##EDTA^{4-}## is also used to treat heavy metal poisoning, as it forms water soluble complexes with them which can then be easily removed by the body. The reaction...
  7. N

    Weird precipitation issue

    We're attempting to measure the immunogenic affects of a particular molecule after subsequent acid and base treatments. As a first version, we're keeping it simple. After all treatment and neutralization, we wind up with 400 uL 0.2 N HCl + 400 uL 0.2 N NaOH + 200 uL H2O. We are getting massive...
  8. V

    Selective precipitation, purity and yield of precipitate

    Homework Statement An aqueous effluent contains 12 M Cd2+ and 10 M Mg2+ as solution of nitrates. Current practice is use NaOH to selectively precipitate the metals. (a) Is it feasible to get 0 Cd impurities in Mg ppt by using NaF instead of NaOH (back up your answer with adequate calculations)...
  9. Teemo

    Solubility and Precipitation of Unknown Ion

    Homework Statement A colorless solution is known to contain one of these ions. Which ion is present if adding dilute HCl produces a white precipitate that dissolves when the solution is warmed? (A) Ag+ (B) Cu2+ (C) Hg22+ (D) Pb2+ Homework Equations N/A The Attempt at a Solution I know it...
  10. J

    Question about precipitation

    The question is in the attachment... "this is an old past exam question" for i) I assume that the pressure will remain constant (I'm not sure) since volume is likely to increase proportion to the decrease in temperature. (Is this correct?) Best Regards