Rain Definition and 145 Threads

Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for hydroelectric power plants and crop irrigation.
The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.
The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming is also causing changes in the precipitation pattern globally, including wetter conditions across eastern North America and drier conditions in the tropics. Antarctica is the driest continent. The globally averaged annual precipitation over land is 715 mm (28.1 in), but over the whole Earth it is much higher at 990 mm (39 in). Climate classification systems such as the Köppen classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall is measured using rain gauges. Rainfall amounts can be estimated by weather radar.
Rain is also known or suspected on other planets, where it may be composed of methane, neon, sulfuric acid, or even iron rather than water.

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  1. ZapperZ

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  2. ZapperZ

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  3. D

    Kinematics of moving car and falling rain

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  4. wolram

    One Step from Rain to Dry: A Strange Encounter

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  5. M

    Water Distribution - Rain Barrel System

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  6. morrobay

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  7. wolram

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  8. P

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  9. T

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  10. Math Jeans

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  11. M

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  12. G

    Work Done by Air Resistance on rain drops

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  13. B

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  14. wolram

    Rainy Day Blues: Wish for Sun to Shine Again

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  15. P

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  16. jambaugh

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  17. G

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  18. P

    Is Rain Water Beneficial for Plant Growth?

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  19. S

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  20. A

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  21. K

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  22. A

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  23. B

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  24. B

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  25. P

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  26. Astronuc

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  27. P

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  28. Hootenanny

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  29. R

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  30. Ivan Seeking

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  31. E

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  32. Mk

    The Unknown Threat: Is Acid Rain Real or Just Hype?

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  33. S

    Does Falling Rain Experience Air Resistance?

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  34. J

    Kinetic energy from rain drops

    Hi, I searched some websites with information about average size and average speed of rain drops, which I used to calculate the kinetic energy of the rain drop just before it hits the ground. My original question was: Is ALL this kinetic energy transferred to the ground (assume a non-elastic...
  35. T

    Find the velocity of the rain with respect to the car and the Earth

    I would like to confirm the answer to this question. A car travels due east with a speed of 50.0 km/h. Raindrops are falling at a constant speed vertically with respect to the Earth. The traces of the rain on the side windows of the car make an angle of 75.0° with the vertical. Find the...
  36. M

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  37. wolram

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  38. B

    What is the volume of a rain drop?

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  39. C

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  40. tandoorichicken

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  41. D

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  42. S

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  43. S

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  44. Monique

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  45. Ivan Seeking

    Putin Orders Fine Weather for St Petersburg Celebration

    "PRESIDENT PUTIN has ordered fine weather for the St Petersburg summit and 300th anniversary festivities next week, and it is unlikely to rain on his parade"
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