What is Precipitation: Definition and 62 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. Sizhe

    Pipe flow with precipitation at boundary

    Homework Statement Consider a plug flow (slippery walls) with a uniform velocity ##U## in a circular pipe of diameter,##d## and length ##L##. The fluid is a supersaturated solution with a concentration ##c##. At the pipe wall, precipitation of solute happens at a net reaction rate per unit area...
  3. I

    How does lifetime of a cyclone affect: precipitation and intensity

    When the total lifetime of an extratropical cyclone over the ocean in the Northern Atlantic-region gets longer (within the same season): - Do the total precipitation sums increase? - Does the precipitation intensities increase? - Does the intensity of the cyclone increase? For example what...
  4. 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.
  5. 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...
  6. T

    Missing precipitation data (hydrology)

    Homework Statement Develop a hydrograph (rainfall intensity vs time) for the precipitation data . Then , estimate the amount of gauge X if there adjacent station precipitation amount of A , B and C are 42.4 , 35.3 and 38.4 respetively . Homework EquationsThe Attempt at a Solution So , i...
  7. Asmaa Mohammad

    Precipitation of colloidal solutions

    Hello, I read about the colloidal solutions in my chemistry book, and came across this sentence: "Emulsoids (a type of colloidal solutions) are difficult to be precipitated, e.g. by concentrated solution of NaCl (removes H2O film by its osmotic power then it neutralize the charges)." I don't...
  8. 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...
  9. 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...
  10. T

    Ksp and precipitation of carbonates

    Homework Statement Homework EquationsThe Attempt at a Solution The lower the Ksp, the more insoluble. Therefore, I chose B since strontium and barium carbonates have the lowest Ksp. However, the question asks which carbonate will precipitate and I know that all carbonates are insoluble. Can...
  11. 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...
  12. N

    Why is my solution precipitating after neutralization with NaOH and HCl?

    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...
  13. 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)...
  14. 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...
  15. J

    What Happens to Pressure During a Temperature Decrease?

    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
  16. Teemo

    Precipitation of Metal Chlorides

    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 The...
  17. C

    Relevance of electrostatic precipitation technology

    Hello. Is electrostatic precipitation technology relevant nowadays? Is it worth making candidate dissertation on it? I am going to investigate back-corona discharge in ESP and operation of ESP under hight inlet dust loadings by means of mathematical modelling (Comsol, my own programs if it's...
  18. J

    Precipitation vs martensitic

    I have been doing some internet learning about precipitation hardening and martensitic transformation, and have some questions. Firstly I'll describe my current understanding: Precipitation hardening (specific to non ferrous alloys) An alloy undergoes solution treatment (basically solid...
  19. Entanglement

    Why are precipitation reactions irreversible?

    Why are precipitation reactions are irreversible as NaCl + AgNO3 --------> AgCl + NaNO3
  20. D

    Slow precipitation of calcium carbonate.

    Hello Everyone, I am working with CaCO3. I want to have the precipitated CaCO3 in the laboratory. The easy way is to mix Na2CO3 and CaCl2. It gives CaCO3 and NaCl but this reaction takes place in a flash. As the reaction rate is high the produced CaCO3 forms powder like substance (the syze of...
  21. F

    Selective Precipitation Chemistry Problem

    Homework Statement A solution of AgNO_{3} is added to a solution containing 0.100 M Cl^{-} and 0.100 CrO_{4}^{2-}. What will be the concentration of the less soluble compund when the more soluble one begins to precipitate?Homework Equations Ksp AgCl = 1.82 x 10^{-10} Ksp Ag2CrO4 = 1.2 x...
  22. S

    Precipitation reactions with AgNO3 and NaCl

    When we add them together, AgCl precipitates as AgCl is insoluble in water so their interactions would cause them to form a solid. However, isn't the interaction between Na+ and Cl- greater than in Ag+ and Cl-? As NaCl has a stronger lattice energy than AgCl. So why is AgCl insoluble while NaCl...
  23. A

    Understanding precipitation reactions

    "When the precipitating agent is added to the solution it causes it to become supersaturated. This starts the process of nucleation where ions and molecules will clump together to form small particles. A small amount of nucleation is necessary to start precipitation. However as the reaction...
  24. A

    Precipitation reaction and supersaturation?

    I read online that when you add a precipitating agent to a solution it initially becomes superstaurated and you have to take measures to decrease this supersaturation. My question is why does it become supersaturated. Really having a hard time understanding this concept.
  25. A

    A question on precipitation reactions

    My chem textbook says that in precipitation reactions you lower the pH of the reaction in order for the precipitate to form quantitatively. It doesn't elaborate at all. What is the meaning of precipitate forming quantitatively?
  26. A

    Precipitation of barium sulfate?

    Precipitation of barium sulfate?? We had to determine the content of sulfate found in lawn food for a class prac. Anyway what we did was to dissolve the fertilizer in HCl and then add barium cholride to it in order to precipitate sulfate as barium sulfate. We later determined its...
  27. M

    What volume of Hg(NO3)2 is required for precipitation?

    Homework Statement Given that 24.0 mL of .170M sodium iodide reacts with .209M mercury (II) nitrate solution according to the below equation (it is balanced). What volume of Hg(NO3)2 is required for complete precipitation? Homework Equations Hg(NO3)2+2NaI ----> HgI2+ 2NaNO3 The...
  28. S

    Standardized precipitation index formula

    Can some help me what really is the formula of the standardized precipitation index and how will it be computed? I am thinking of using the index to classify the 40 years into dry year, average year , or wet year using total annual rainfall data. I understand that SPI is an index based on the...
  29. P

    Understanding Alloy Microstructures: Slow Cooling vs Precipitation Hardening

    how are microstructures of alloys different when slowly cooled and precipitation hardened?
  30. A

    How is the Huff Method Used for Temporal Distribution of Rainfall?

    Hello! Does anyone have (or if is possible an example) about Huff Method utilized for temporal distribution of rainfall. Thanks in advance.
  31. J

    What Is the Role of Ethanol in Precipitating Salts?

    Homework Statement what is the purpose of adding ethanol in step 5 in the following description? http://www.creative-chemistry.org.uk...s/N-ch5-08.pdf Homework Equations The Attempt at a Solution Does adding ethanol make the liquid phase (which is now a homogenous mixture) less...
  32. A

    Ksp, saturated solutions and precipitation (Ionic Equilibria)

    I have the following doubts while understanding the concept. Please help me solve them :- (1) What is a precipitate exactly? While determining the Ksp values, we say that there in a dynamic equilibrium between the solid undissolved solute in contact with the solution and the ions in solution...
  33. B

    Urine/seawater precipitation salts

    A boat toilet ( called 'heads') uses seawater to flush the waste overboard or into a holding tank. Over time there is a serious "furring up" of the waste pipes - not the inlet pipes - which implies that there are precipitation salts produced from the reaction of the seawater with, presumably...
  34. C

    Precipitation hardening Vs Martensitic Transformation

    hi everyone, i am try to figure out what is the differences of precipitation hardening and martensitic transformation as both are also considered as hardening mechanism??
  35. A

    Understanding Precipitation Hardening in Metal Strength

    Hi guys, I am doing a powerpoint on the hammer, and i need to say something about precipitation hardening, and I am having a bit of trouble understanding it. could someone please explain it simply Thanks
  36. V

    Precipitation reactions for sparingly soluble compounds?

    When 2 ionic solutions are mixed and the reaction gives a sparingly soluble product, it is possible to write an ionic equation for the mixing of the solutions.
  37. S

    Precipitation from saturated solution

    Homework Statement How many grams of PbS will precipitate from 1.00 L of a saturated solution of PbSo4 if the concentration of S2- is adjusted to give a concentration of 1.00E-17? Homework Equations PbSO4 Ksp=1.6E-8 PbS Ksp=2.5E-27 The Attempt at a Solution I assumed that there...
  38. K

    Stoichiometry of Precipitation Reactions

    Homework Statement What mass of iron(III) chlorate is needed to precipitate all the chromate ions from 234 mL of a 0.100 M lithium chromate solution. Homework Equations The Attempt at a Solution we just started precipitates and my teacher didnt explain the procedure very well...
  39. J

    Precipitation problem

    Homework Statement consider a solution that initially contains 0.15M Sr(NO3)2 and 0.25M Ba(NO3)2. The sulfate ion concentration is gradually increased by the slow addition of solid Na2SO4. a. What is the sulfate ion concentration when barium sulfate just begins to precipitate b. what is the...
  40. L

    Gravimetric Analysis- precipitation method

    Homework Statement 1.046g of the hydrated chloride of a certain metal were dissolved in water and silver chloride was precipitated by the addition of a slight excess of silver nitrate solution. After purification the silver chloride had a mass of 1.231g. Calculate the percentage of chlorine...
  41. S

    Simple precipitation question?

    Hi there. I'm just wanting to know the most important reason why barium chloride is chosen over lead chloride as the precipitation agent when trying to determine, by gravimetric analysis, how much sulfate is in a sample. I think it's probably due to BaCl2 having a higher solubility, but...
  42. X

    Record precipitation in the UK

    Recently, extremely heavy rain has fallen in the United Kingdom. Some locations received over 12 inches of rain within a 24 hour period! This is likely a UK record for the greatest 24 hr rainfall based on records going back to 1914...
  43. B

    Why is S2- Added Slowly for Efficient Precipitation of Ag+ and S2-?

    Why do we have to add S2- slowly and gradually for precipitation to take place??
  44. H

    What Causes Precipitation When Silver Nitrate Reacts with Different Ions?

    We were doing anion identification tests in the lab today and I noticed silver nitrate had a tendency to react with the samples and something would precipitate out. I also noticed silver nitrate is the reactant used for chloride tests. Is what precipitates out in that case silver chloride? Also...
  45. M

    Effect of Precipitation Hardening on Elastic Modulus

    Hey guys, we have ordered some spring rings made out of Inconel 718. For some reason the company didn't finish the heat treat and the parts are just annealed, in the "dead-soft" condition. I need to evaluate if these things are usable (they are actually supposed to be soft and were designed...
  46. M

    Ksp vs Ka: What's the difference and how does it relate to precipitation?

    Homework Statement NaCl is added slowly to a solution that is 0.010M in each Cu+, Ag+ and Au+. Ksp's are 1.9x10^-7, 1.8x10^-10 and 2.0x10^-13 respectively. Which compound will precipitate first? Can anyone tell me how the Ksp is different from Ka? and the relationship to precipitation?
  47. P

    Will Mixing CaCl2 and NaOH Solutions Form a Precipitate?

    Help please! Here's the question I'm having problems with: The solubility product of calcium hydroxide, Ca(OH)2, is 7.9 x 10^-6 at 25 degrees celcius. Will a precipitate form when 100mL of 0.10 mol/L of CaCl2 solution and 50.0 mL of 0.070 mol/L of NaOH solution are combined? Do I...
  48. Ivan Seeking

    Environment Dept. probes strange precipitation

  49. L

    Chemistry- Selective Precipitation

    Homework Statement My molarity [I] is wrong which keeps me from ding the rest of this problem...any help would be greatly appreciated. A researcher has a 450.0 mL solution that is 0.421 M in Hg2(NO3)2 and 0.0191 M in Pb(NO3)2. She plans to add solid potassium iodide to separate the...