eTwinning project activity

1. What is rain?
Rainis liquidwaterinthe formof dropletsthathave condensedfromatmosphericwatervaporand
thenprecipitated—thatis,becomeheavyenoughtofall undergravity.Rainisamajor componentof
the watercycle and is responsible fordepositingmostof the freshwateronthe Earth. It provides
suitable conditionsformanytypesof ecosystems,aswell aswaterforhydroelectricpowerplantsand
crop irrigation.
The major cause of rainproductionismoisture movingalongthree-dimensionalzonesof
temperature andmoisture contrastsknownasweatherfronts.If enoughmoisture andupward
motionispresent,precipitationfallsfromconvectiveclouds(thosewithstrongupwardvertical
motion) suchas cumulonimbus(thunderclouds) whichcanorganize intonarrow rainbands.In
mountainousareas,heavyprecipitationispossiblewhere upslopeflow ismaximizedwithin

2. windwardsidesof the terrainatelevationwhich forcesmoistairtocondense andfall outas rainfall
alongthe sidesof mountains.Onthe leewardside of mountains,desertclimatescanexistdue tothe
dry air causedbydownslope flow whichcausesheatinganddryingof the air mass.The movementof
the monsoontrough,or intertropical convergence zone,bringsrainyseasonstosavannahclimes.