# دورة المياه فى الطبيعه hydrological, or water cycle



## عمروعلى3 (24 يوليو 2006)

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[BLINK]بعيدا عن الخرسانه والرمل والزلط[/BLINK]

This is called the hydrological, or water cycle:





From the time the earth was formed, water has been endlessly circulating. This circulation is known as the hydrologic cycle. Groundwater is part of this continuous cycle as water evaporates, forms clouds, and returns to earth as precipitation.
The Process
Surface water is evaporated from the earth by the energy of the sun. The water vapor forms clouds in the sky. Depending on the temperature and weather conditions, the water vapor condenses and falls to the earth as different types of precipitation. Some precipitation runs from high areas to low areas on the earth's surface. This is known as surface runoff. Other precipitation seeps into the ground and is stored as groundwater.
Groundwater is water that fills the spaces between rocks and soil particles underground, in much the same way as water fills a sponge. Groundwater begins as precipitation and soaks into the ground where it is stored in underground geological water systems called aquifers. Sometimes groundwater feeds springs, lakes, and other surface waters or is drawn out of the ground by humans. The water then can evaporate, form clouds, and return to the earth to begin the cycle over again. 

Sunshine 
The sun shines on water in rivers, lakes, streams, wetlands and oceans and makes the water warmer. This turns the water into vapor or steam. The water vapor leaves the lake or ocean or river and goes into the air, where it becomes a cloud. 
Evaporation 
Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river or lake or ocean and goes into the air, where it becomes a cloud. 
Rain 
When the temperature is warm, like during the spring or summer, clouds get so full of water that rain starts to fall. The rain falls onto the land and runs into streams and rivers. The water in the streams and rivers runs into lakes and finally into the ocean. Some of the rain that falls soaks into the ground and stays there until plants drink it or until it goes deep enough into the ground that it is called "groundwater" and goes to people's wells. 
Snow 
Snow is just like rain except it falls when the air is cold, like during late fall and winter. Snow usually stays on top of the ground until it melts, then it turns into water and runs into streams and rivers. Some of the water from melted snow also goes into the ground for plants and people to drink. 
Mountains and Ice 
Some of the snow that falls onto mountains stays there a long time because it is so cold most of the time at the top of mountains. This snow turns into ice and sometimes becomes glaciers. Snow and ice on the top of mountains can stay there sometimes for hundreds of years before it finally melts and runs into the streams and rivers. 
Rivers and Streams 
Rivers and streams carry the water that comes from rain and melted snow into the ocean. They sometimes can carry this water a long way. The Mississippi River in the middle of the United States carries rain and melted snow from Minnesota and Canada all the way to the Gulf of Mexico. When the weather is warm, sometimes the sun makes the rivers and streams warm, some of the water turns into steam or vapor, and it leaves the river and goes into the air where it becomes a cloud. 
Oceans 
Oceans are like really big lakes. Rivers and streams carry all of the water that comes from rain and melted snow into the oceans. When water gets into the oceans, it mixes and becomes salty. When the sun shines on the oceans, the water gets warmer and becomes vapor, which goes into the air and becomes a cloud. Most of the water on the earth is in the oceans.​

Carbon Dioxide, Smoke, Sulfur 




Water is sometimes known as the universal solvent. It has a 
tendency to dissolve a little bit of everything it touches. Dust, smoke from industry, carbon dioxide, spores and smog may be absorbed by water droplets

Acid Rain 




For example, if it dissolves sulfur from industrial smokestacks, it can form acid rain. This increases its capacity to dissolve other substances. The water vapor in clouds eventually condenses and falls back to earth as rain, sleet, hail or snow.


Calcium, Hydrogen Sulfide, Iron, Magnesium, Sodium, Radioactivity 




As water runs over the surface it can become cloudy, even muddy. Then, as water seeps down through the ground, it may dissolve a little bit of the minerals and other substances that could be present.


Odor, TCE, PCB, Trihalomethanes 




By the time water returns to rivers, lakes or underground aquifers, it may have accumulated amounts of the elements it has contacted.


Fungicides, Herbicides, Insecticides




Along the way bacteria, chemicals, agricultural byproducts, fertilizers, insecticides and other man-made wastes may also enter the water. Even after reaching a home, it can continue to dissolve materials such as lead from solder in plumbing pipes


[BLINK]Did you know...?[/BLINK]
•	97% of the water on earth is in the oceans 
•	Only 3% of the water on earth is freshwater 
•	About 2.4% of the water on earth is permanently frozen in glaciers and at the polar ice caps 
•	About 1/2 of 1 % of the water on earth is groundwater 
•	Only about 1/100 of 1% of the water on earth is in the rivers and lakes 
•	It takes 39,090 gallons of water to make a new car, including the tires 
•	Over 17,000,000 houses use private wells for their drinking water supply 
•	A person can live about a month without food, but can live only about 1 week without water​

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## هند2006 (13 نوفمبر 2006)

السلام عليكم
بارك الله فيك على هذا الموضوع
مفيد من ناحية المعلومات وحتى المصطلحات الانكليزية


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## descovery_2000 (13 نوفمبر 2006)

بارك الله فبك استاذي العزيز على هذة المعلومات المفيدة 
ومن الله التوفيق


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## ماجدان (3 مارس 2008)

شكرا وجزالك الله خير 
سالدان للهندسهوالإنشاءات


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