Sunday, 24 January 2010
Friday, 15 January 2010
Earthquake physics has undergone a revolution during the past decade, thanks to new insights from lab experiments, field studies of exhumed faults and better theories.
But the nature and behavior of the forces that keep faults from moving and then suddenly fail are still unknown. And when faults do move, something is missing—there is little to no evidence of the extremely high levels of friction and melting that would be expected to follow above ground when two giant rocks slid against each other.
Most earthquakes happen where tectonic plates meet and glide against each other. Quakes occur when the frictional stress of the movement exceeds the strength of the rocks, causing a failure at a fault line. Aggressive displacement of the Earth's crust follows, leading to a release of elastic strain energy. This energy takes the form of shock waves that radiate and constitute an earthquake.
Earthquakes typically occur along the jigsaw-puzzle pieces of Earth's crust, called plates, which move relative to one another, most of the time at an invisibly slow pace. In the case of the
Tuesday, 12 January 2010
With increased prosperity, people are consuming more meat and dairy products every year. Global meat production is projected to more than double from 229 million tones in 1999/2001 to 465 million tones in 2050, while milk output is set to climb from 580 to 1043 million tones.
A Japanese study showed that producing a kilogram of beef leads to the emission of greenhouse gases with a global warming potential equivalent to 36.4 kilograms of carbon dioxide (CO2). It also releases fertilizing compounds equivalent to 340 grams of sulphur dioxide and 59 grams of phosphate, and consumes 169 mega joules of energy. In other words, a kilogram of beef is responsible for the equivalent of the amount of CO2 emitted by the average European car every 250 kilometers, and burns enough energy to light a 100-watt bulb for nearly 20 days (New Scientist magazine, 18 July 2007) The following tables indicates the CO2 production in kg CO2 equivalents per kg of meat depending on the animal:
1 kg of meat from produces kg CO2e
Monday, 11 January 2010
As a result of the current discussion how further global warming could be prevented or at least mitigated, the recovery of nuclear power seems to be in everybody's - or at least in many politician's - mind. It it attractive to see that in many suggestions to mitigate global warming.
Advantages of nuclear power generation:
- Nuclear power generation does emit relatively low amounts of carbon dioxide (CO2). The emissions of green house gases and therefore the contribution of nuclear power plants to global warming is therefore relatively little.
- This technology is readily available, it does not have to be developed first.
- It is possible to generate a high amount of electrical energy in one single plant.
Disadvantages of nuclear power generation:
- The waste from nuclear energy is extremely dangerous and it has to be carefully looked after for several thousand years
- High risks: Despite a generally high security standard, accidents can still happen. It is technically impossible to build a plant with 100% security. A small probability of failure will always last. The consequences of an accident would be absolutely devastating both for human being as for the nature
- Nuclear waste could be preferred targets for terrorist attacks. No atomic energy plant in the world could withstand an attack similar to 9/11 in Yew York.
- During the operation of nuclear power plants, radioactive waste is produced, which in turn can be used for the production of nuclear weapons.
- The energy source for nuclear energy is Uranium. Uranium is a scarce resource, its supply is estimated to last only for the next 30 to 60 years depending on the actual demand.
Sunday, 10 January 2010
When sunlight reaches Earth's outside some is absorbed and warms the earth and most of the rest is radiated back to the atmosphere at a longer wavelength than the sun light. Some of these longer wavelengths are absorbed by greenhouse gases in the atmosphere before they are lost to space. The absorption of this long wave radiant energy warms the atmosphere. These greenhouse gases act like a mirror and reflect back to the Earth some of the heat energy which would otherwise be lost to space. The reflecting back of heat energy by the atmosphere is called the "greenhouse effect".
The major natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds); carbon dioxide CO2, which causes 9-26%; methane, which causes 4-9%, and ozone, which causes 3-7%. It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hydrofluoric, hydro fluorocarbons, per fluorocarbons and chlorofluorocarbons.
Almost 100% of the observed temperature increase over the last 50 years has been due to the increase in the atmosphere of greenhouse gas concentrations like water vapour, carbon dioxide (CO2), methane and ozone. Greenhouse gases are those gases that contribute to the greenhouse effect (see below). The largest contributing source of greenhouse gas is the burning of fossil fuels leading to the emission of carbon dioxide.
I want to share how climate change is affecting the daily life and economy in
Bangladesh is experiencing frequent severe weather patterns, in the form of floods, cyclones, heavy rains, droughts, river erosion and salinity intrusion due to climate change.
An increasing world population and harmful industrialization worldwide are the main causes of climate change. The severity of storms, droughts, rainfall, floods and other natural disasters has been increasing in Asian countries, and in