Earth Atmosphere and rejuvenation process of earth: From “A short history of nearly everything” by Bill Bryson
Posted by: adonis49 on: May 24, 2011
Earth Atmosphere from “A short history of nearly everything” by Bill Bryson
Without our atmosphere that extends 190 kilometers, Earth would be a ball of ice averaging minus 50 degrees Celsius. Altogether, the gaseous padding is equivalent to 4.5 meters of protective concrete. The immediate layer is the troposphere that represents 80% of the atmosphere mass and contains water vapor and oxygen; it is 16 kilometers’ thick at the equator and around 11 kilometers in the temperate climates.
The crowding of atoms in the troposphere and, although they travel at a mere speed of 8 millionths of a centimeter per second, their collisions provide enough warmth for our survival.
Human can live to altitude around 4,500 meters by developing large chests and lungs and increasing the density of oxygen-bearing red blood cells by a third but we are not made for high altitudes.
At an altitude of over 6,000 meters, every step demands a colossal effort of will. The temperature drops about 1.6 degrees with every 1,000 meters you climb. Around an altitude of 10,000 the temperature reaches minus 57 degrees.
A rise of an inch in the barometer represents half a ton of air piled upon us, and the reason we don’t feel crushed is that our body is almost of water that is not compressible. Only 0.035% of the Earth’s fresh water is floating around as cloud soaked water vapor.
The next layer is the stratosphere, followed by the mesosphere and the ionosphere or thermosphere where temperature reaches 1,500 degrees Celsius.
The rejuvenating processes on Earth
Huge amount of heat, energy and electricity are created and transferred around the globe every second. A single thunderstorm contains an energy equivalent to 4 days use of electricity for the whole USA.
At any moment an average of 1,800 thunderstorms are in progress around the world. Day and night about 100 lightning bolts hit the ground every second.
A typical weather front may consist of 750 million tons of cold air pinned beneath a billion tons of warmer air; the strength of wind grows exponentially so that a wind blowing at 300 kilometers an hour is 100 times stronger than 30 kilometers per hour wind. Thus, a tropical hurricane can release in 24 hours as much energy as France uses in a year.
Air always flows from areas of high pressure coming from the equator to areas of low pressure to keep pressure in balance. Moist and warm air from the equator rises until it hits the barrier of the troposphere and spreads out. As it travels away and cools, it sinks. When it hits bottom, some of the sinking air looks for an area of low pressure to fill and then heads back for the equator, completing the circuit through convection.
This convection process is explained by the Coriolis effect that results from the fact that Earth spins at 1,675 kilometers an hour at the equator but the spin reduces its velocity as it is closer to the poles to become almost negligible; a straight line seems to curve to the right at the north hemisphere and to the left at the southern hemisphere. The Coriolis effects sends hurricanes spinning off like tops.
The other current that is the main agent of heat transfer is known as thermohaline circulation. For example, England and Ireland are very lucky that the Atlantic is more saline than the Pacific; the denser saline water sink at the bottom, and aided by the Coriolis effect, huge amount of warm water are charred by the Gulf Stream to warm the weather and keep many part of Western Europe from becoming icy like Canada and Russia.
As the water of the Atlantic gets to the vicinity of Europe, it grows denser and sinks to great depths and begins a slow trip back to the southern hemisphere. When they reach Antarctica, they are caught up in the Antarctic Circumpolar Current and driven onward into the Pacific. This process takes 1,500 years for water to travel from the North Atlantic to the mid-Pacific, but the volume of heat and water they move are very considerable and the influence on the climate is enormous.
Unfortunately, with the increase of the greenhouse effect, the higher melting rate of the Greenland ice is diluting the Atlantic Ocean and could disrupt the cycle disastrously.
Earth experienced many periods of Ice Age; we are in one Ice Age but within a period of a warmer one. Just figure an ice sheet 800 meter thick and many kilometers long and wide progressing at 150 meters a year; no obstacles can resist the progress of this monster ice sheet: boulders are carried away and placed at mountain tops and many islands were thus attached to mainland such as Cape Code, Long island, and Nantucket in the east of the USA.
The Swiss Natural History professor Louis Agassie borrowed that idea from his colleague Jean de Charpentier and then toured the world lecturing his theory and traveling and climbing the craggiest Alpine peaks. The USA was the homes that embraced his idea and offered him a chair in Harvard and build him a first-rate Museum of Comparative Zoology.
The cause of ice age starts in cool summers that prevent snow to melt in the poles and incoming sunlight bouncing off by the reflective surface and thus, exacerbating the cooling effect and encouraging more snow to fall and stick. It is not necessarily the amount of snow that causes ice sheets but the fact that snow is lasting. The process is self-enlarging and unstoppable.
The last chapter of “A short history of nearly everything” by Bill Bryson described how Man came to exist 100,000 years ago. Modern human is so recent on Earth that the genetic differences among 55 chimpanzees are much larger than the entire human species.
Yet, modern human has managed to damage extensively Earth, its environment, and thousands of species in such a short period. Apparently, human activities are causing more than one thousand species to go extinct per week.
The nineteenth century, especially in the USA and Britain, experienced a deliberate wiping out of any animal species that was not considered a pet such as animals living in farms.
The States in America paid out bounties for eastern mountain lions and other pests. The dodo flightless bird was wiped out from the island of Mauritius in 1693 simply because the ship crews needed to have something to do.
In the USA, thirty genera of very large animals disappeared; ten million mammoth carcasses are thought to be frozen in the Siberian tundra. A walrus-like creature called Steller’s sea cow, 9 meters in length and weighting 10 tones got extinct in the mid 18th century. The golden head and emerald-green Carolina parakeet was wiped out because it was considered a pest by farmers. The dog-like Tasmanian tiger was wiped out in Australia by 1936.
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