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Sharpen Your General Knowledge
Shamim Ansary:
How Is the Correct Time Decided?
Ancient man probably measured time by daylight and darkness, or by the rising and setting of the sun. He also probably noticed that as the earth turned, the sun was directly over his head only once a day, in the middle of the day. This he called midday.
But this midday time was different in different parts of the ancient world since the sun is seen differently, depending on the location from which man was looking at it.
When travel was slow hundreds of years ago and no radios, telephones, or television connected all parts of the world, this was not too much of a problem. But as people all over the world needed to be more and more in contact with each other, a correct reference to time was needed.
In 1884, an international conference was held in Washington, D.C. to set up a time system for the world. Using knowledge man had gained from the ancient Babylonians, who had divided the circle of the earth into 360°, the scientists divided the earth into 24 time zones, each one covering 15° of longitude, and totaling 360°. Each time zone differed from the one next to it by one hour, since the earth rotates 15° in one hour.
The conference also decided that the starting point of noon would be an imaginary longitudinal line running through Greenwich, England. Heading east, the next time zone, one hour later, would be 1 P.M. when it was noon in Greenwich. Heading west, the next time zone would be one hour earlier, 11 A.M., when it was noon in Greenwich.
Since New York is 5 time zones west of Greenwich, or 5 hours earlier, it is 7 A.M. in New York when it is noon in Greenwich. Tokyo, Japan, is 9 time zones east of Greenwich, or 9 hours later, so it is 9 P.M. in Tokyo when it is noon in Greenwich.
The place on the globe where the point 12 hours east of Greenwich meets the point 12 hours west of Greenwich is called the International Date Line. It is exactly us, halfway around the world, 180° from Greenwich, and runs through the Pacific Ocean.
A traveler heading west from the United States towards Japan on Sunday would cross the International Date Line and find that it was then Monday. When he returned from Japan, say on Tuesday, he would cross the International Date Line and find himself back on Monday.
A traveler crossing the International Date Line can actually live through 2 Tuesdays (or 2 of any day) in one week!
Shamim Ansary:
What is the Russian Federation and When Did the Soviet Union Collapse and Form 15 Independent Republics?
The Russian Federation is Russia’s offical name.
The Russian Federation, which occupies about three-fourths of the land that once was the Soviet Union, is made up of 21 autonomous republics, 50 oblasts (or regions), 6 krays (or provinces), 2 federal cities (Moscow and St. Petersburg), 1 autonomous oblast, and 10 autonomous okrugs (or autonomous territories).
Russia is a federal semi-presidential republic, comprising 83 federal subjects.
An unsuccessful military coup directed against Soviet leader Mikhail Gorbachev in August 1991 led to the collapse of the Soviet Union which resulted in the formation of the Russian Federation.
The USSR officially dissolved in December 1991 and Boris Yeltsin was elected the President of Russia.
Shamim Ansary:
Why Are There So Many Different Types of Rain From Heavy To Light and What Causes Different Raindrop Sizes?
Elongated stair rods are an illusion. Large raindrops actually tend to be flattened by air resistance.
When they land they are called in Afrikaans, and I understand, in Welsh, “old women with clubs.†The circular sheet of splashing water suggests a wide skirt and the centrally rebounding droplet a cudgel.
Droplet size is the main factor in creating different kinds of rain.
This depends on conditions at the time of formation, particularly humidity, temperature, and the number of airborne nuclei such as dust particles.
For example, moderate numbers of nuclei in moist updrafts tend to promote drops that grow large, because there is plenty of water for them and they cannot come down before they grow heavy enough to fall faster than they are lifted.
When nuclei are crowded they compete with each other and can only form small droplets that may evaporate before they reach the ground.
In still air, big drops fall fast and hard.
Drops that are about 0.4 inch in diameter reach speeds of around 20 miles per hour, at which point their own slipstream tears them into smaller droplets, unless they are partly frozen. This limits raindrop size.
However, a large number of falling raindrops can create a downdraft, increasing the downward velocity a drop can achieve without splitting, while strong horizontal winds can more than double the speed of impact.
Rainfall intensity depends mainly on the depth of the cloud and the strength of the updrafts.
Rapidly rising air produces fast condensation of water droplets and large amounts of rain, mostly when the cloud extends high enough for ice crystals to form among supercooled water droplets.
Shallow clouds with weak updrafts only give drizzle, which rarely falls faster than 10 feet per second. Large raindrops can reach a terminal velocity of about 32 feet per second.
Their fall speed increases with size until the diameter approaches 0.25 inches, at which point wind resistance flattens the base, increases the drag and prevents further acceleration.
However, if the rain is caught in a “downburst†where an air column is descending at 65 feet per second or more, the rain hits the ground harder. Downbursts are often associated with cumulonimbus clouds that contain almost vertical air currents. The weight of precipitation in the cloud may be enough to trigger a downburst.
Rain from deep flat cloud layers is usually caused by slow diagonal ascent along a sloping frontal surface.
Such rain is persistent but seldom heavy. This can change if prolonged lifting makes the layer unstable. Then massive turrets containing strong updrafts grow vertically out of the layer.
These can produce heavy downpours from a cloud mass which had previously only given moderate rain.
Shamim Ansary:
How long does an earthquake last?
If you count tremors prior to the quake and aftershocks, earthquakes can last for months. But the central event lasts only seconds or minutes.
The great San Francisco earthquake of 1906 began when the ground shuddered for about a minute at 5:11 A.M., April 18. Ten seconds of quiet followed. At 5:12 A.M., the major quake-7.9 on the Richter scale—began.
Three minutes later, it was over, leaving thousands of buildings in pieces, broken gas mains, buckled streets, and raging fires. Ultimately, 75 percent of the city was destroyed.
The disastrous earthquake in Mexico City on the morning of September 19, 1985, also lasted 3 minutes. In that time, 250 buildings were leveled. The next day another quake destroyed another 150 buildings and put a stop to the first earthquake’s relief work.
Shamim Ansary:
How Can You Pass 24 Hours in Less Than 60 Minutes?
The lines that divide the world’s time zones meet at the North and South Poles, so the zones get narrower as they near’ the poles.
An Alaskan airline offers a flight over the Arctic regions that includes a circular flight around the North Pole. If you were to circle the North Pole, you’d pass through all the world’s times zones in less than an hour!
If it were noon when you started to circle the pole, you’d soon pass the line marking the beginning of the next time zone, and it would become one o’clock. A few minutes later, you’d have to move your watch ahead another hour.
As the flight continued, you’d keep moving your watch ahead, past midnight, through the morning, until you returned to your starting point, before clocks there had reached one o’clock.
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