Understanding the Water Cycle

Key Definitions

• Water Cycle: A continuous natural pattern of water movement and state change on, above, and below Earth's surface.
• Melting: The change from solid to liquid, requiring thermal energy gain.
• Sublimation: The change from solid to gas, requiring thermal energy gain.
• Evaporation: The change from liquid to gas, requiring thermal energy gain.
• Condensation: The change from gas to liquid, requiring thermal energy loss.
• Deposition: The change from gas to solid, requiring thermal energy loss.
• Freezing: The change from liquid to solid, requiring thermal energy loss.
• Runoff: Water from precipitation flowing over Earth's surface.
• Groundwater: Water seeping through soil and rock cracks, feeding springs and wells.
• Aquifer: A groundwater-saturated geological formation of loose rock or soil.
• Water table: The upper boundary/depth of the saturated zone in an aquifer.
• Precipitation: Water falling to Earth's surface in solid or liquid form.
• Polar ice sheet: A frozen ice field covering the North or South Pole.
• Icecap: A large, permanent ice-covered land area.
• Glacier: A slow-moving river of ice formed from accumulated snow over years.
• Water treatment: Removing dangerous substances from water for safe use.
• Floc: Sticky clumps of alum, sand, and waste solids formed during water treatment.
• Sustainability: Meeting present needs without compromising future generations' ability to meet theirs.

Water Characteristics

• Water is crucial for drinking, agriculture, firefighting, and industry.
• Water is a solvent facilitating the dissolution of substances like oxygen, carbon dioxide, and salts.
• Over half the human body is water which is essential for transporting substances, facilitating chemical reactions, and regulating body temperature.
• Water exists in solid, liquid, and gaseous states.
• Solid (Ice): Particles vibrate in fixed positions which retains shape.
• Liquid (Water): Particles move freely while remaining close.
• Gas (Water Vapor): Particles move quickly and are far apart, has no fixed shape.

The Water Cycle

• Powered by the sun the water cycle is a self-renewing and constant process that moves water around the Earth.
• Evaporation: Liquid water turns into vapor by absorbing heat.
• Condensation: Water vapor cools and forms droplets in clouds.
• Precipitation: Water falls as rain, snow, sleet, or hail.
• Runoff: Water flows over land surfaces into bodies of water.
• Groundwater Infiltration: Water seeps into the ground and collects in aquifers.
• Melting & Freezing: Ice transforms into liquid water and vice versa.
• Sublimation & Deposition: Ice directly changes into vapor and vice versa.
• Oceans, lakes, and rivers serve as surface water sources.
• Glaciers and polar ice caps store frozen water.
• Soil and plants absorb water for growth and sustenance.
• Groundwater & aquifers store water underground.

Making Water Drinkable

• Natural water contains impurities like harmful bacteria, dirt, and chemicals that make it unsafe for consumption.
• Screening removes large objects.
• Coagulation & Flocculation: Alum creates floc to trap dirt.
• Sedimentation: Floc settles at the bottom of undisturbed water.
• Filtration: Water passes through sand and charcoal filters.
• Disinfection: Chlorine or ozone kills bacteria and viruses.
• Clean water is stored and then distributed to homes.
• Reverse Osmosis: Filters contaminants using a fine membrane.
• Ultraviolet (UV) Treatment: Kills bacteria with UV light.
• Boiling: Kills bacteria but does not remove chemicals.
• Water Softeners: Remove minerals like calcium and magnesium.

Addressing Water Shortages

• Reducing unnecessary water use with shorter showers and leak repairs helps conserve water.
• Rainwater can be used for irrigation to conserve community water.
• Conserving Water
• Building reservoirs enables rainwater storage.
• Wells can be developed to tap into groundwater.
• Investing in desalination initiatives help treat and purify water.
• Emergency water purification tablets can provide potable emergency water.
• Educating communities help awareness of conservation.
• Regulating industrial water use prevents pollution.
• Innovative Water Solutions
• Cloud seeding creates rain using chemicals.
• Drip irrigation saves water by targeting plant roots.