Water is essential to all life and is about 70 percent of the weight of most plants and animals. The unique physical properties of water enables it to play a dynamic role in shaping the landscape and creating special habitats for all organisms. Water can be found in three physical states, as liquid, solid, and gas. It is colorless, odorless, transparent to visible light, and opaque to infrared radiation.
Water vapor in the atmosphere allows sunlight to pass through to the earth’s surface, where the sunlight heats the ground, evaporates water, or is used in photosynthesis. Water has low viscosity and flows easily. Water has its greatest density at 4 degrees Celsius. Therefore lake freeze at the surface and have water temperature at the bottom of 4 degrees Celsius. Water expands upon freezing, some ice is less dense than water it floats.
Many organisms can survive the winter in the liquid cold water of deep lakes where no freezing takes place. Water evaporates readily into the vapor state and consumes heat in the process. Water vapor is less dense than air therefore moist air is less dense and more buoyant that dry air. Moist air rise in the atmosphere until it is cooled to the condensation temperature at which level clouds are formed.
Plants absorb water through their roots, on the other hand solar heating of the leaves removes water by causing release of water vapor into the atmosphere, this process is called
. Through the process of
the water flows from roots to leaves and transports from the soil all the vital nutrients needed by the plant for growth. The water in the leaves is necessary for photosynthesis and growth. A lack of water inhibits plant growth and adequate water supply promotes growth on the other hand too much water can be a limiting factor to those plants that adapt to using lesser amounts. Some plants have adapted to growing in water.