Hydrology Review

1. Hydrology Review Water Cycle, Atmosphere, Weather, and Climate

2. Hydrology • Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic (water) cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist.

3. The Water Cycle Movement of water from water sources to air, onto land, into the ground, and then back to water sources.

4. Stages of Water Cycle • Evaporation • Condensation • Precipitation • Percolation • Runoff

5. Evaporation • The change in state from a liquid to a gas (water vapor). • Remember Water=H2O. When solar energy excites these molecules the H2O splits into H-H-O (1 hydrogen, 1 hydrogen, and 1 oxygen) all gasses!

6. Condensation • Clouds form as air cools to its dew point. • Classified by form and by altitude at which they form. • 3 Main Types: • Cumulus- puffy white with flat bottoms • Stratus- form layers • Cirrus- thin, feathery, white clouds at high altitudes

7. Clouds with –nimbus or nimbo- included usually produce precipitation • Cirro- is used to describe clouds at high altitudes. • Alto- describes clouds at middle altitudes.

8. Precipitation • Occurs when water vapor condenses in the atmosphere and fall back to Earth in solid or liquid form. • Examples: rain, sleet, snow, hail

9. River Systems • Streams arevery small and run into larger rivers. • Tributaries are smaller streamsthat flow into the larger stream or river. • Drainage basin- watershed- land drained by river system. • Drainage basins are separated by area called a divide. • Channel is the path that a stream follows.

10. Stages of a River Youthful River: erodes channel deeper not wider, flows quickly b/c it’s gradient is steep, waterfalls Mature River: erodes channel wider not deeper, gradient is not too steep, few waterfalls, many tributaries Old River: low gradient, low eroding, wide and flat river b/c deposits sediment on banks, meanders

11. Rejuvenated River: occur where Earth’s surface is raised by tectonic forces, steep gradient

12. Erosion • Is the removal and transportation of soil and rock. • Rate of stream erosion is affected by many factors: • Stream’s gradient • Discharge • Speed • Load

13. Deposition • Occurs when eroded soil and rock are dropped or settled. • Alluvium is the material deposited by rivers and streams. • Deltas are deposits of alluvium at a river’s mouth. • Alluvial fans are deposits at the base of a mountain. • Flood plains are rich farming areas b/c flooding brings new soil to the area.

14. Water Underground • Ground water is located below the Earth’s surface. • It can dissolve rock, especially limestone. • Zone of aeration and zone of saturation meet at boundary called water table. • An aquifer is a porous and permeable rock layer through which ground water flows. • Sinkholes form when the water table is lower than the roof of an underground cave.

15. Springs are a natural way that water reaches the surface. • Wells are made by humans to tap the water underground. • Caves and sinkholes form from the erosion of limestone by groundwater.

16. Meteorology-Study of the Atmosphere • The atmosphere is a mixture of gases. • Nitrogen and oxygen make up most of the Earth’s atmosphere. • Air Pressure decreases as altitude increases. • The composition of atmospheric layers affects their temperature.

17. Temperature differences in the atmosphere area result of the way solar energy is absorbed as it moves downward through the atmosphere.

18. Layers of the Atmosphere • Troposphere- lowest atmospheric layer. • It is the layer in which we live • Densest layer • All weather occurs here • Stratosphere- contains the ozone layer which protects us from harmful UV radiation

19. Layers of the Atmosphere • Mesosphere- coldest atmospheric layer • Thermosphere- uppermost layer of the atmosphere • Remember that as you move through the atmosphere, temperature varies!! It changes! It’s different!

20. Meteorology-Weather • Weather is the condition of the atmosphere at a certain time and place. • It is affected by the amount of water vapor in the air. • The water cycle describes the movement of water above, on, and below Earth’s surface. • Water is continuously moving and changing state as it moves through the water cycle.

21. Humidity describes the amount of water vapor in the air. • Relative humidity is a way to express humidity. • When the temperature of the air cools to its dew point, the air has reached saturation and condensation occurs.

22. Air Masses and Fronts • Air masses are characterized by their moisture content and temperature. • Air masses form over source regions. • Have similar temperature and moisture content throughout • A front occurs where 2 air masses meet. • Specific types of weather are associated with each front. • Four major types of fronts are: • Cold • Warm • Occluded • Stationary fronts

23. Difference in air pressure cause: • cyclones, which bring stormy weather • Anticyclones, which bring dry, clear weather

24. Severe Weather • Thunderstorms are intense weather systems that produce strong winds, heavy rain, lightning, and thunder. • Lightningis a large electrical discharge that occurs between 2 oppositely charged surfaces. • It releases a great deal of energy and can be very dangerous.

25. Tornadosare small, rotating columns of air that touch the ground and can cause severe damage. • Hurricanes are large, rotating tropical weather systems. • Cause strong winds and can cause severe property damage.

26. Forecasting the Weather • Meteorologists use several instruments to forecast the weather. • Weather balloons • Thermometers-Measure Temperature • Barometers-measures atmospheric pressure in “bars” • Anemometers-measures wind speeds • Windsocks-measures wind direction • Weather vanes-ditto • Radar • Weather satellites

27. What is Climate? • Weather is a condition of the atmosphere at a particular time. • This condition includes temperature, humidity, precipitation, wind, and visibility. • Climate is the average weather condition in an area over a long period of time. • The higher the latitude, the cooler the climate.

28. Climate is determined by temperature and precipitation. • Climate is controlled by factors such as latitude, elevation, wind patterns, local geography, and ocean surface currents. • As elevation increases, temperature decreases.

29. The amount of solar energy an area receives is determined by the area’s latitude. • The seasons are a result the tilt of the Earth’s axis and its path around the sun. • The amount of moisture carried by prevailing winds affects the amount of precipitation that falls.

30. Prevailing winds affect the climate of an area by the amount of moisture they carry. • Mountains influence an area’s climate by affecting both temperature and precipitation. • Large bodies of water and ocean currents influence the climate of an area by affecting the temperature of the air over the water.

31. The 3 climate zones of the world are: • Tropical zone • Temperate zone • Polar zone

32. Changes in Climate • The Earth’s climate experiences glacial and interglacial periods. • The Milankovitch theory states that the Earth’s climate changes as its orbit and the tilt of its axis change. • Climate changes can be caused by volcanic eruptions, asteroid impact, the sun’s cycle, and by global warming.

33. Excess carbon dioxide is believed to contribute to global warming.