A stream drainage area is also called a watershed. The drainage area of a stream encompasses all the land from which surface runoff flows into that stream. Where the slopes are steepest and the hills the highest, the streams will be the most energetic and the rate of erosion will be fastest. The higher the hill, the more gravitational energy there is to drive the stream. Streams flow downhill due to the force of gravity. Streams erode dirt and rocks, transport the sediment, and redeposit it in new locations, shaping the earth’s surface into a system of stream valleys. Most valleys on earth are the product of streams. Over longer intervals of time the same processes we’ve imagined on the construction site have built systems of streams and stream valleys on the surface of the earth. If not prevented, the channels may continue to deepen and erode soil from the construction site. A network of streams, including tributaries, has formed. Soon, the water excavates small channels, known as rills, in the dirt. At first the water saturates the ground and begins to flow downhill across the surface of the slope in a thin sheet. It is interesting to watch water on a recently bulldozed construction site with a slope. A small brook in a meadow and the Amazon River are both streams. What Are Streams?Ī stream is flow of water, driven by gravity, in a natural channel, on land. By eroding sediment from uplifted areas and creating landforms made of deposited sediment in lower areas, streams shape the earth’s surface more than glaciers do, more than waves on a beach do, and far more than wind does. Streams sculpt and shape the earth’s surface by eroding, transporting, and depositing sediment. She adds that this pattern of more frequent, extreme shifts north and south has never been seen before in her 290-year record.Streams have a major role in geology. "Since 1960 we get more years when the jet is in an extreme position," Trouet says, either in its northernmost or southernmost position. What surprised the scientists was that the jet stream's meandering has become more frequent. And that helped them establish the normal pattern of the jet stream's fluctuations. These revealed what kind of weather Europe had each year. Researchers at the University of Arizona and the Swiss Federal Research Institute studied tree rings to get a fix on how widely and how often the jet stream meanders.īiologist Valerie Trouet took samples from four species of trees in Europe, including Scots pine, dating back to 1725. And that affects how warm or rainy it is on those continents. When those meanders occur over the Atlantic and the Pacific Oceans, it can alter pressure systems and wind patterns at lower latitudes in Europe and North America. That river meanders north and south along the way, however. The jet stream is like a river of wind that circles the Northern Hemisphere continuously. Severe weather events like this one may be linked to more frequent fluctuations in the polar jet stream, according to a new study.Ī new study suggests that the polar jet stream has been fluctuating more than normal as it passes over the parts of the Northern Hemisphere, and that's affecting weather in Europe and North America. Gale force winds and heavy rain brought disruption to large parts of the country. Waves crash onto the beach near Brighton Pier in England, in January 2007.
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