Water is very special. It is one of the most plentiful substances on earth, and it is a liquid at the temperatures and pressures that exist in most places on the surface of our planet. Because of this, it plays a vital role in our biosphere ... its behaviour as it absorbs energy from the sun is critical to the existence of life on earth. On these pages we'll look at some of the characteristics of this unusual substance. Specific Heat Capacity The Comfort Zone Heats of Fusion and Vaporization Density and Life on Earth Water Molecules and Their Properties Water Vapour and the Atmosphere Resources This material is primarily designed as a supplement to the Alberta Science 10 course, but may also be of interest and benefit to students at other levels or in other courses.