Water+Cycle

Some good websites:

http://www.bbc.co.uk/schools/riversandcoasts/water_cycle/rivers/pg_02_flash.shtml

http://en.wikipedia.org/wiki/Water_cycle

colours of clouds:

http://www.usatoday.com/weather/resources/askjack/2003-07-29-gray-clouds_x.htm

summary (of above, more on storm clouds:

http://wiki.answers.com/Q/Why_are_the_storm_clouds_grey

Kheng Hun