The Water Cycle:Earth’s Water is Always in Circulation

Posted on March 22, 2008 by Rashid Faridi

The Earth’s water is always in circulation. It has been recycled for the last 3 billion years. This process is called the water cycle.

The cycle starts when the sun’s heat evaporates water from the oceans into the atmosphere to form clouds. When the conditions are just right, the clouds release water as rain or snow. Most of the rain falls in the oceans, but the rest falls onto land. Rivers and streams collect water from the ground and return it to the ocean so the whole cycle can start all over again. The water cycle never ends because the salty ocean water constantly supplies fresh water to the continents.

One process which tranfers water from the ground back to the atmosphere is evaporation. Evaporation is when water passes from a liquid phase to a gas phase. Rates of evaporation of water depend on things like the temperature, humidity, and wind.

Water that is held in lakes (Inland Water Bodies)and rivers evaporates directly into the atmosphere. Some of the water in the ground may also be returned to the atmosphere by way of evaporation through the soil surface. Of course, the ocean is the greatest source for water evaporated into the atmosphere.Transpiration is the process by which plants return water to the atmosphere. After absorbing water from the ground, plants release water through their leaves. Transpiration helps plants stay cool, in the same way perspiration keeps humans and animals cool.

source: http://www.windows.ucar.edu

Posted in Class Notes, water | 3 Comments

Currents of the Ocean

Posted on March 22, 2008 by Rashid Faridi

This illustration shows the circulation of the ocean’s surface water. Names of the major ocean currents are noted. Warm currents are noted in the color red and cold currents are noted in the color blue.
Click on image for full size (260K JPEG)
Windows Original

There are two main sections of ocean water: the surface layer and the the deep waters. The surface layer is the layer at the top of the ocean that is well mixed by waves, tides, and weather events like rain or a hurricane. The surface layer sits on top of the deep water because the surface layer is less dense. The depth of the surface layer varies depending on location and season, but the depth is typically a couple hundred meters. There is a boundary layer between the surface layer and the deep waters that is called the the pycnocline (meaning rapid change of density). The pycnocline is caused by rapid changes of temperature and salinity.Surface water movement takes place in the form of currents. Currents move ocean water horizontally at the ocean’s surface. Surface currents are driven mainly by the wind. Other forces such as the Coriolis effect and the location of land masses do affect surface current patterns. In fact, huge circular patterns called current gyres can be seen when looking at the world’s ocean currents. From the equator to middle latitudes, the circular motion is clockwise in the Northern Hemisphere and counterclockwise in the Southern hemisphere. Near the poles of the Earth, there is a tendency for the gyres to flow in the opposite direction. This circulation of water helps spread energy from the Sun. The Sun warms water at the equator and then water and heat are transported to higher latitudes.

Major ocean currents of the world include :

  • North & South Equatorial Current
  • Equatorial Counter Current
  • North Atlantic Drift
  • Gulf Stream
  • Kuroshio Current (off of Japan)
  • Antarctic Circumpolar Current
  • East Australian current

source:http://www.windows.ucar.edu

Related articles
Posted in oceans | 3 Comments

Historical Data on Global Warming

Posted on March 22, 2008 by Rashid Faridi

Historical Data on Global Warming
provided by U.S. Government Agencies

By Dan Pangburn, P.E.

I have been researching the global warming issue for months. I am a licensed Mechanical Engineer with an MSc in Mechanical Engineering. The following is a brief verbal description of some of my sources and findings with graphics that show these findings.

Climate obviously has changed and will continue to change. But the observation that ice is melting, which can look dramatic on TV, does not show that human activity is the cause. The assertion that humans have or ever can have a significant influence on climate such as by limiting the use of fossil fuel (a.k.a. limiting human production of carbon dioxide) is not supported by any historical record. Avoid the group-think ‘consensus science’ and de facto censorship by Climate Scientists. Directly interrogate official government data that taxpayers have paid for from ORNL and NOAA as follows:

The temperature has varied substantially while the carbon dioxide in the atmosphere2 exhibits a smooth progressive rise. Note on this graph that prior to about 1910, and again from 1944 to about 1976, temperature showed a decreasing trend while atmospheric carbon dioxide level was increasing. Thus, as shown on this graph, until 1998 the average global temperature trend and atmospheric carbon dioxide level went in the same direction about half the time and in opposite directions the other half. The temperature rise that received so much attention and contributed to the Global Warming mistake lasted for about 22 years from 1976 to 1998. The temperature stopped significant increase in 1998. According to NOAA data, the average global temperature trended down during 2007 to lower than it was in 1998. This down-trend continues with the average for the first two months of 2008 being substantially lower.

full story

Posted in Global Warming | Leave a comment

The Physical Ocean

Posted on March 22, 2008 by Rashid Faridi

Physical oceanography is the study of the physical properties and dynamic processes of the oceans. Physical oceanographers study the interaction of the ocean with the atmosphere, how the ocean stores and releases heat, the physical properties (or chemical content) of water throughout the ocean, and the formation and movement of currents and coastal dynamics. In order to understand these phenomena, researchers at NASA measure ocean surface topography, sea surface temperature, the speed and direction of the winds over the ocean, and soon, sea surface salinity (salt content). From these data, scientists can further study ocean currents, and sea ice.

Satellites provide a double advantage over traditional ship-based measuring systems as they are able to provide continuous measurements on a global scale. A single global snapshot – which would be expensive and time-consuming, but possible from ships or buoys – fails to convey how the physical state of the ocean is changing. With satellite data, scientists can understand not only how the ocean behaves at a given point in time, but also how the ocean changes and fluctuates. For example the patterns of heat distribution within the ocean and the geographic extent of current systems affect climate and weather. A displacement of weather patterns can extend summer weather or lead to droughts or floods.

The Physical Ocean
Ocean Surface Topography
NASA uses extremely precise measurements of the height of the ocean acquired from orbiting satellite instruments to map the topography of the ocean surface. Ocean Surface Topography (OST) data contains information that has practical applications in such areas as the study of worldwide weather and climate patterns, the monitoring of sea level evolution, and the protection of our ocean fisheries.
Sea Surface Temperature
Instruments aboard NASA satellites use their vantage point from space to collect global measurements of the ocean’s surface temperature. By developing global, detailed, and decades-long views of Sea Surface Temperature (SST), data obtained from NASA satellites provide the basis for prediction of climate change, ocean currents, and global climate patterns like the potent El Niño-La Niña cycles.
Sea Surface Winds
Winds are the largest source of momentum for the ocean surface. Winds have an impact on both individual currents and complete current systems. When observing ocean phenomenon, it is critical to consider winds as part of what we measure.
Sea Surface Salinity
Sea Surface Salinity (SSS) tells us the about the concentration of dissolved salts in the upper centimeter of the ocean surface. Even small variations in SSS can have dramatic effects on the water cycle and ocean circulation.
Ocean Surface Currents
The ocean is constantly in motion, with currents that travel both on the surface and in the depths. These movements carry water vast distances. Only from space can the true extent of currents be tracked in real time. NASA satellites employ a variety of instruments to interpret ocean currents.
Sea Ice
Sea ice is formed when ocean water is cooled below its freezing temperature. Sea ice is important to the study of oceans because it impacts oceanic chemical and physical properties, density structure, oceanic dynamics, and exchanges between the ocean and the atmosphere. A variety of NASA instruments are used to measure and study sea ice from space.

source:http://science.hq.nasa.gov/ocean

Posted in oceans | Leave a comment