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Lec 11-12 Hydrosphere, and Water Cycle.pptx
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- 2. The Water Cycle •Watercycle also known as the Hydrological cycle or Hydraulic cycle is the continuous movement of water above or below the surface of land. •Water never leaves the Earth. It is constantly being cycled through the atmosphere, ocean, and land. This process, known as the Water Cycle, is driven by energy from the sun.
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- 9. Water Cycle • Thereis always the same amount of water on Earth. • Water appears in different states (liquid, gas or solid form). • Water continually move between the atmosphere, the oceans and the continents.
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- 12. Evaporation • During partof the water cycle, the sun heats up liquid water and changes it to a gas by the process of evaporation. • Water that evaporates from Earth’s oceans, lakes, rivers, and moist soil rises up into the atmosphere.
- 13. Evapo-transpiration: •Evapo-transpiration is water evaporatingfrom the ground and transpiration by plants. •Evapo-transpiration is also the way water vapour-enters the atmosphere •About 90% of atmospheric water comes from evaporation, while the remaining 10% is from transpiration. •Water is evaporated from lakes, streams, oceans, and plants.
- 14. Condensation • Condensation isthe process by which water vapor changes into water. Water vapor condenses to form dew, fog or clouds. • As water (in the form of gas) rises higher in the atmosphere, it starts to cool and become a liquid again.
- 15. Condensation can form:Fog, Dew, and Clouds •Fog: •Fog forms when air near the surface is cold and nearly saturated with water. Now when water from the ground evaporates, it condenses immediately forming tiny water droplets that create a low-lying cloud we call fog.
- 16. Dew: • Dew formsat night when air becomes saturated with water vapor. When this saturated air comes in contact with plants or other objects it condenses, leaving tiny water droplets behind on the object.
- 17. Clouds: • When theair containing water vapor is heated by the sun, it rises into the atmosphere by convection. The water vapor in the air is then cooled by the colder air higher in the atmosphere causing the relative humidity to increase. • As the relative humidity increases, the air eventually becomes saturated. The water vapor then condenses into tiny water droplets around particles of dust or salt in the air. These tiny water droplets make up clouds.
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- 19. Precipitation • When thewater in the clouds gets too heavy, the water falls back to the earth. • This is called precipitation. • Precipitation is the process that occurs when water particles fall from the atmosphere and reach the ground. • Precipitated water may fall into water bodies or on land. •It can then go to streams or penetrate in the soil.
- 20. Types of Precipitation 1.Drizzle 2. Rain 3. Freezing rain 4. Sleet 5. Snow 6. Hail
- 25. Hail • ▪ Hailis a product of very intense thunderstorms. • ▪ Hail is rarely seen when the surface air temperature is below freezing.
- 28. GroundWater • Groundwater iswater that has drained through surface layers of soil and rock until it reaches a layer of rock material through which it cannot pass, or can pass only very slowly. • This results in the accumulation of water in the rock layers above this impermeable layer. The water is stored in gaps in the rock, or between the particles of which the rock is composed. Rock which retains water in this way is called an aquifer.
- 30. Interception: • Interception refersto precipitation that does not reach the soil, but is instead intercepted by the leaves and branches of plants and the forest floor.
- 31. Infiltration •Some precipitation seepsinto the groundwater and is stored in layers of rock below the surface of the Earth. •This water stays there for varying amounts of time. Some water may evaporate into the hydrologic cycle within days, while other water will stay in the ground for centuries or more. •This process of precipitation seeping into the groundwater is called infiltration. •It is measured in inches per hour or millimeters per hour. •It is measured using infiltrometer.
- 32. Runoff • When rainfalls on the land, some of the water is absorbed into the ground forming pockets of water called groundwater. Most groundwater eventually returns to the ocean. • Other precipitation runs directly into streams or rivers. Water that collects in rivers, streams, and oceans is called runoff. • Runoff is precipitation that did not get absorbed into the soil, or did not evaporate. Runoff causes erosion, and also carry chemicals and substances on the ground surface.
- 33. Storage of Water •Thereare three basic water storage places: in •atmosphere, on earth’s surface, and in the ground. Surface storage places are: ocean, lake, reservoirs, glaciers. •Underground storage occurs in soil, in the cracks of rocks etc.
- 34. Earth Ocean • EarthOcean are joined together known as World Ocean • Oceans regulates Earth Environment
- 35. Function of ocean: •absorb & store energy from sun. • This regulates temperatures in earth’s atmosphere • Ocean absorbs half the solar radiation • Ocean absorbs & releases heat more slowly than land. Temperature in atmosphere changes more slowly than it would if there were no ocean. • Local temperatures affected by currents that carry warm water by land areas
- 36. Threats • Pollution • ClimateChange • Overfishing • Global Warming • Melting of Glaciers • Drought at some places and Extreme Rains at other places