Fresh Water Earth Science Ms. Hall

Water is a necessity for life!!! Water appears to be every where 70% of the Earth is covered by oceans 97 of our water is salt water Leaving only 3% as fresh water But 2% of that is captured up in ice Only 1% of the Earths water is potable (Drinkable) water!!!

Water is special Water is a polar molecule – Repels fats – Attracted to other polar molecules (alcohols etc.) Water makes hydrogen bonds – Same volume of water is smaller than ice – Ice floats on water – Capillary action – Water/ surface tension

Water is special II Cohesion – ability to stick to itself Adhesion – ability to stick to other things Capillary action – ability to creep upwards

Hydrologic cycle Water cycle- the continuous movement of water from land to air and back to land. Evaporation  Condensation  Precipitation  Back through again

Evaporation Phase change of water on land to water vapor in the air Uses suns energy to change phase Water evaporates from the oceans, fresh water, plants, animals and soil. Water vapor is carried by the winds in the form of clouds. Transpiration – evaporation off of plants

Condensation & precipitation It condenses in the clouds Condensation is the phase change from gas to liquid Water then precipitates back to the land It can be in the form of rain, sleet, snow etc…

Where does it go? Water may sit in ponds and lakes move into streams and rivers Soak up in the soil to move in under ground rivers called aquifers. Often times up north, in cold areas, fresh water is captured into a glacier.

Surface runoff Rain and melting snow that do not sink into the soil become surface runoff flowing into rivers and streams Or toward the ocean

Factors that affect surface runoff Soil type: larger pore space percolates better Soil condition: dry vs. saturated # of plants: roots soak up the water Seasons/ amount of precipitation, frozen ground Amount of concrete: urban vs. rural areas

Water sheds All this water tends to go toward the ocean. Watershed is the land area which drains all the excess water the ground can’t hold ( surface runoff) Rivulets  streams  rivers

Where does it go? Sometimes the precipitation, and runoff, including whatever's in and on the ground, end up in low places, forming bodies of water.

Bodies of water Lakes – Large bodies of standing water where the light does not penetrate the bottom Ponds – smaller bodies of water where the light penetrates the entire bottom, much plant growth. Reservoirs – man-made lakes for drinking water supplies or hydroelectric power. Vernal pools – temporary bodies of water, important breeding grounds for small amphibians and insects