Mechanical Convection

Why Glaciers and Polar Ice are Melting Faster

The International Panel on Climate Change (IPCC) is the agency that gives us scientifically approved and governmentally sanctioned views of complex issues relating to climate change.

Its view on ice melting has been especially cautious. The panel report predicts that ice on glaciers on mountains and in Polar ice sheets is melting and is going to raise levels of world oceans by 7 to 23 inches by 2100. Sea level rise has two major components; water expands when being heated and water from melting ice on lands flows to the oceans and raises their levels. Exact measurements of sea levels are extremely difficult. Atmospheric pressure, Earth movement, global wind patterns, and ocean currents affect readings.

We all have read that mountain glaciers are receding or disappearing, we have read that the Polar Bears are threatened, and we may have read that snow making equipment is now used in skiing areas.

The culprit for what is happening to glaciers and Polar ice sheets is global warming. However, the fast acceleration of ice melting during the last few decades can not be explained fully by rising global temperatures.

A specialty in engineering science deals with the prediction of heat and mass transfer in industry. It is a discipline that is shunned by many engineering students. Heat transfer courses deal with three quite different modes of heat transport. Heat is transferred by conduction, by convection, and by radiation. If you have ever burned a finger by touching a hot surface you are aware of these three modes. If you touch a hot surface you feel pain almost immediately. Heat is conducted to your finger and the nerves in your finger report pain to protect you. If you hold your finger under the faucet and cool it with cold water, your finger is being cooled by a moving liquid and you feel the effects of convection. You can feel radiation, when sitting in front of a burning fireplace.

All three processes take place when ice is melting. During summer, warmer winds strike ice surfaces and heat the surface. First the snow cover is melted. Only after the snow cover has melted completely, can the ice be heated. During the day the ice surface my get wet, during night the melted water on top freezes again. Why are these processes important?

When winds blow over a snow or ice surface, the warmer air transfers heat to it. In the process the air cools down and looses its ability to heat. Only warm air can transfer heat and melt snow or ice. After giving off its heat and lowering its temperature, the blowing air has lost its excess energy. If only air temperatures were responsible for ice melting, we would experience snow and ice melting rates that would be only marginally higher than those 100 years ago and melting of ice deposits would not be threatening, yet.

Radiation heat transfer from surface winds is the one variable that has changed dramatically during the last century. Air now contains one third more carbon dioxide and other greenhouse gases. Greenhouse gases are optically active, they emit heat by radiation. Therefore, the air that is blowing over ice surfaces has increased its radiating power by a third, too. This is why ice melting is accelerating.

There is an additional, more insidious reason. When thermal radiation hits the surface of a snow blanket, it melts only the surface of the snow. When thermal radiation hits the surface of wet ice, another process takes over. Thermal radiation is able to enter the ice itself and will penetrate deeply if the ice is clean. Dirty ice absorbs heat within a shorter distance. The ice is heated from the inside! Worse, the heat inside the ice mass cannot get out anymore. During summer, the ice is heated from within. During winter, when the ice is covered by a snow blanket, the heat cannot escape. Instead, it penetrates the entire ice mass by conduction.

The next summer, after the snow on top has melted, the ice continues to soak up heat again. The amount of heat each year is small but continues to accumulate for years and decades. Shortly before melting, the ice looses mechanical strength rapidly and becomes prone to throw off large pieces on its outer periphery. Sometimes another phenomenon can be observed. If the ice sits atop a layer of mud or silt, the mud looses strength at the same time when the ice is weakening. The melting mud serves as a lubricant and may let the ice sheet move downhill.

Can we do anything to reverse these threatening processes? Realistically, nothing. Reversing atmospheric greenhouse gas concentrations would be effective. While it is conceptually possible, it will take more than fifty years before we can expect to begin using large scale greenhouse gas removal technology. Otherwise, we can protect bare ice with a snow or dirt blanket. Right now, there seem to be no other alternatives.

Obviously, the described processes are not part of the models that forecast ice melting and sea level rises. Therefore, the world must prepare itself for an ugly surprise. Sea levels will rise much faster than the IPCC has been predicting. Prudent governments will prepare for rises that are twice as high as predicted by the IPCC in the year 2100.

About the Author

Dr. Hemsath recently published the book: CLIMATE CHANGE - GOLD RUSH OR DISASTER? For 50 years he has worked as scientist, process engineer, Corporate Vice President of R&D, Company President, CEO, and Inventor. He holds more than 60 US Patents. He is working on a new book: "THE SOLUTION FOR ENDING GLOBAL WARMING AND CLIMATE CHANGE". Go to http://www.thermalexpert.com

Passive Solar Heating - Supplying A Person's Residence That Pleasant Welcoming Feeling The Natural Way

Men and women have been using solar power for centuries. Ancient Greeks used the sun to heat their residences. Given that they understood that the placement of the sun differed along with the changing seasons, they were able to develop their structures to ensure that the sun directly hit them in the wintertime, but not inside the summer time when they wished to stay cool.

Some homes are still warmed up this way. This technique is called solar heating panel. Another demonstration of this technique is when sunlight shines on a pool and heats up the water.

If you are going to take advantage of the remarkable technology that is passive solar, a good beginning point what be a definition of just what exactly is meant by passive solar. Solar makes reference to the sun, which offers us with unbelievable degrees of light and warmth each and daily.

Passive suggests that you will discover no mechanised or moving components used inside the technology involved, in this case passive solar heating. You may perhaps believe of this as performing things naturally, instead of mechanically.

Passive solar homes make use of your building sections, the positioning of the home, and a variety of design features to provide passive solar heat to the building. Windows that face the sun as much throughout the day as possible are utilized to bring solar light within the building, where it can be absorbed by the flooring, walls along with other such building pieces, where it really is converted to thermal energy (heat).

In a entirely passive solar heating system, the entire energy (heat) flow is by natural means (conduction, natural convection, and radiation. ) By contrast, an active solar heating system employs pumps, blowers and/or fans to move warmed up fluid from the solar collectors to the heated space, from the collectors to solar heat storage region, and from heat storage to the heated space.

Designs contain main components that collect, offer you storage for and cautiously send out gains of solar heat equally into every and each and just about every single portion of the location becoming heated. You commonly don't want particular mechanical type gear to make particular that heat is carried out, converted or radiated all the way by means of your space.

Style the property to collect sun light. A house making use of passive solar heating really should have an big location with windows and supply instant access to the sunlight devoid of having foliage, brush or other things hindering it.

Style the building's floor technique to enhance solar heating. Orient the solar collection surfaces, as example appropriate glazing in windows and doors, within 15 degrees of accurate south, if attainable.

Other solar heating panel style traits include sunspaces and trombe walls. A sunspace (which is a lot like a greenhouse) is built on the south side of a building. As sunlight passes through glass or other glazing, it warms the sunspace.

Correct ventilation allows the heat to circulate in to the building. However, a trombe wall is a very solid, south-facing wall, which is painted black and made of a material that absorbs a lot of heat.

A pane of glass or plastic glazing, set up a few inches in front of the wall, helps hold within the heat. The wall gets hotter bit by bit during the day. Then as it cools steadily throughout the evening, it emits its heat into the building.

How is chemical, mechanical, radiant, sound, and nuclear energy transferred.?

I would like to know if chemical mechanical, radiant, sound, and nuclear energy transferred by conduction, convection, and radiation. Oh--and if they need a medium. Please specify each.

Go here

http://www.buzzle.com/articles/energy-types.html

Goodbye

Thermo Scientific Heratherm Ovens