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rainwater

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 ***ulonimbus (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. F

    Rain,Bath,Greywater recycling

    Is anyone interested in a two butt rain/bathwater/greywater recycling project?
  2. C

    Plumb rainwater to in ground cistern under house?

    I'm trying to pipe rainwater into my cistern under my house. I'm trying to find an overflow controle method. 4" auto valves are to expensive. Thought about putting a ring around in to raise the top up far enough to put an overflow pipe but I don't think I could get it to seal right. Is there a...
  3. M

    Will Building Control permit a combined rainwater / sewage system?

    Our Victorian house's rainwater down-pipes are connected to the foul-water sewer. In order to accomodate new wider French windows I want to move the existing soil stack. When they see the plans or site do you think Building Control will want to alter the existing rainwater arrangements? All the...
  4. MDDIY2022

    Reducing diameter of rainwater drain pipe ?

    Hi everyone, I have an outdoor open drain which runs along the side of our house and then into an underground 5" pipe which takes the water away to the sewer. I want to pipe the open drain so that the water isn't exposed when it runs along the side of the house. Please see my attached diagram...
  5. G

    Condense pipe connected to rainwater pipe

    Hi all, My gas engineer connected the condense pipe to the rainwater pipe and now it’s returning water back into the boiler when there is a heavy rain. We installed a one way flow valve internally however the pressure of the rainwater coming into the condense pipe is still causing issues...
  6. B

    Potential drainage issue - next door extension

    We live in a terraced row (SW London) and our neighbours are currently in the process of finalising their extension. There is a potential drainage issue (their rainwater drainage) for which they have advised us of a course of action to resolve it. Before agreeing, we would like a bit of...
  7. Z

    Combined rainwater and soil stack?

    Hi, we have moved our upstairs bathroom so need to put a new soil stack on the outside wall. In the place where we want to put it is a rainwater pipe with a "bucket style" opening at the top, (sorry I don't know the correct term), because it is a flat-roof property so it catches the water from...
  8. C

    Loud Noise in rainwater pipes

    Hi, I live in a 10 storey block of flats on the ground floor and inside some walls of my flat are rainwater pipes that run down from the roof. Couple of months ago I started hearing a loud bang in the walls where those RW pipes are hidden whenever it rains heavily. The building manager sent a...
  9. S

    Unvented cylinder discharge into 1980s Marley plastic rainwater hopper and pipe?

    I live in a shared building with a flat above me. My upstairs neighbour has just fitted an unvented hot water cylinder. The plumber has run the 22mm copper discharge pipe into the old plastic Marley hopper and downpipe, which discharges straight into the sewer. This downpipe also carries...
  10. L

    Can I add an overflow (i.e. secondary) rainwater drain in an internal lightwell that feeds into a bathroom's soil pipe?

    I would appreciate some advice. I have a flat on the 3rd floor of a converted house, which has a lightwell in the middle of the flat. The bottom of the lightwell reaches the 3rd floor (my flat’s floor level) and has a roof lantern for the flat on the 2nd floor. I plan to build a small bathroom...
  11. S

    68mm rainwater to 110mm Soil

    I am currently looking at the possibility of adding a downstairs toilet and basin and the only viable drain is a 68mm rainwater on the outside of the wall where the cloakroom will be. I have combined drains at my property, the 110mm drain is reduced down to 68mm CI and runs as a rainwater to the...
  12. G

    Condensate drain connection to rainwater drain

    I'm going to have to get by boiler replaced which means provision needs to be made for a condensate drain as the old boiler didn't have one. The boiler is in the garage, that is part of the house, if that makes sense. The house was built in 1999. There is no convenient internal drain. Outside...
  13. K

    Can I terminate a rainwater down pipe into a waste water gully outside the kitchen?

    Hi Just came across a customer whom had an extension built many years ago but It seems as though the builder forgot to allow for rainwater to be terminated. He's run a rain water pipe all the way from the back of the single storey extension, along the side and to the front of the house. This...
  14. A

    Outdoor rainwater shower: Which pump?

    I am hoping that this pump will work for an outdoor rain water shower that I am currently setting up outside on our balcony. I contacted the company to ask for advise on this but they haven't responded. If this won't work do any of you know if there is another pump that will work? Garden Pump...
  15. SimonG

    What You Think? Rainwater Into Waste.

    Next door to where I'm working had their bathroom done recently. Chopped down stack and stuck aav on top and cut rainwater in. Neighbour was concerned because water comes out the rainwater connection. Separate rain and soil sewers.
  16. giznorm

    Soil pipe and rainwater - is this set up legal?

    Hello everyone, I could do with some opinions on the drainage set up at a house I am buying and would really appreciate your advice. I've been searching online for weeks but got conflicting information. I'm trying to see if the changes made to drainage are legal. The previous owner moved the...
  17. G

    Kitchen discharging into rainwater via bathroom drain

    Hi, getting a big renovation done in a tenement flat in Scotland, my builder has connected the kitchen drainage into the bathroom drainage all discharging into one pipe which feeds into an existing branch of the rainwater pipe. All the flats bathrooms lead to this pipe. Aside from the fact my...
  18. B

    Rain ingress through boiler flue

    Hi Guys I have an Ideal Logic System s24 which was installed approx 2 years, and haven't had any problems with it. This morning there was a wet patch below the boiler, and multiple drops of water under the boiling casing. I turned offbthe power and popped the cover off just to look, and it is...
  19. Rob Foster

    Here is a rainwater recycling scheme we designed and built

    In mid Wales in 1999 it serviced a big nursing home and commercial laundry
  20. Karl

    Kingspan rainwater harvesting system

    hey hope you guys can help me out I’m after the non-return valve for the rainwater system, but it’s not a standard nrv it’s got a tapping in it for the pressure transducer and I can’t seem to find the part!! Anyone know where I could find it? Thanks
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