DIU Activities > Alumni
Sharpen Your General Knowledge
Shamim Ansary:
How Much Water Do Clouds Hold and How Does the Size and Color of a Cloud Affect How Much Water It Can Hold?
The amount of water inside a cloud is not different from the amount of water in the clear air around it.
However, while the clear air contains water vapor, inside the cloud the air is saturated with water vapor and it has condensed out to produce the cloud.
The difference between the two states is caused by temperature differences rather than the water content.
The color of a cloud doesn’t make much difference either.
In the higher part of a cloud, the water is in the form of ice crystals. Lower down it is a mixture of ice and liquid water. The color of the cloud depends mainly on this ice/water mixture and the size of the water droplets, and less on the total amount of water.
An estimate of a cloud’s water content can be obtained from the amount of rain the cloud can produce.
If the entire atmosphere were saturated with water and it all fell in a steady stream, this could produce some 1.4 inches of rain, while the thickest actual clouds produce about 0.8 inches.
Cloudbursts can produce 2 inches or more, but this requires additional moisture from the surrounding atmosphere, which means such events are localized.
The heaviest cloudbursts roughly follow the following equation: the rainfall in inches equals 162.5 multiplied by the square root of the time in minutes that it has been raining.
A more typical shower produces a fraction of an inch of rain, at a rate of perhaps 0.04 inches per minute. Normally 1 inch of rain corresponds to 900,000 cubic feet of water weighing 4,000 tons per cubic miles of cloud, though the thickest clouds can contain up to 20 times as much.
You can also estimate the amount of water from the volume of the cloud.
By volume, the fraction of the cloud filled with water is about 1 millionth, or 0.0001 percent. The cross-section area of a cloud can be measured from its shadow. A small cloud 1,000 feet by 1,000 feet and 500 feet high has a volume of 500 million cubic feet, of which roughly 500 cubic feet will be water, weighing 15 tons.
Even if you can’t calculate the precise amount of water in a cloud, these numbers may still impress your friends.
Sadly, just looking at a cloud does not give very precise information about how much water it contains.
The color of a cloud depends entirely on the relative position of the viewer and the physical structure of the cloud. Its apparent size is dependent on the altitude of the cloud, and this is generally very difficult to judge from a single observation point.
But knowing exactly how much water is contained in a cloud is important for producing accurate weather forecasts.
The choice of frequency for a Doppler radar beam is very important.
If the beam interacts too strongly with the water in a cloud, in terms of either reflecting or attenuating the signal, then the radar will have only a limited ability to penetrate cloud structure. If the interaction with water is too weak, then no useful information can be returned at all.
One facility in England can analyze and extract a huge variety of data and has a maximum range of around 100 miles. It is able to provide information on droplet density, size, speed, and whether the droplets are water or ice.
Using this tool, your reader could work out fairly accurately the total water content contained within a cloud and, from the structure of the cloud, how likely it is to start raining, this technique has proved very useful at the Wimbledon tennis championships in past years, which are, of course, notorious for being interrupted by downpours.
Such radars help to produce detailed information on weather, from tracking hurricanes to helping to produce your daily weather forecast and predicting areas of turbulence on aircraft flights.
And remember that kinetic energy rises with the square of the velocity.
Shamim Ansary:
Where Did the Engagement Ring Come From and How Did the Tradition Originate?
The diamond engagement ring was introduced by the Venetians, who discovered the diamond’s value in the sixteenth century.
But betrothal gifts hadn’t included rings until 860 A.D., when Pope Nicholas I decreed that a ring of value must be given as a statement of nuptial intent.
It was also mentioned that if the man called off the wedding, the jilted bride kept the ring.
If the woman ended the engagement, she was to return the ring and be sent to a nunnery.
Shamim Ansary:
How Were Time Zones Invented and When?
It would be very confusing if the clock said midday in one place and the sun was high in the sky, but in another place at midday the sky was pitch-black and full of stars. Thank goodness someone had the bright idea of time zones.
Universal Time. Depending where you are on the planet, it might be the middle of the day or the middle of the night, because the Earth is orbiting the Sun. Of course, before time zones clocks weren’t set at the same time for everyone and no one ate their lunch at 3 a.m. or had breakfast at bedtime.
People used the Sun as their guide and the time was set locally, when the Sun was overhead, it was midday. As new ways to travel and communicate were invented, knowing the exact time in different parts of the world became more and more important, and a standard time was needed.
Sir Sandford Fleming first proposed time zones for the whole world in 1876. In 1884 an international conference at the Royal Observatory in Greenwich, London, adopted the time zones we know today. Planet Earth rotates on its axis 15 degrees every hour, so the world is divided into 24 15-degree sections, with the clocks in each section set an hour apart (at least, that’s how it works for most of the world).
The zones are all measured from Greenwich, which the 1884 conference decided was the Prime Meridian. The time at Greenwich is known as Greenwich Mean Time or, more grandly, Universal Time.
The Pacific country of Kiribati used to have two different time zones. The eastern half of the country was a whole day and two hours behind the western half! In 1995 the time zone was changed so that Kiribati clocks all told the same time.
Shamim Ansary:
Why Are the Numbers On a Keyboard Arranged With the Lowest Numbers On the Bottom and Phones Are the Opposite?
Mechanical adding machines, based on rotating wheels, always have the 0 button adjacent to the 1 button.
By convention, most old adding machines had the numbers increasing in value from the bottom and this may be a hangover from when the machines had levers on the wheels rather than buttons.
When the numbers were put on to a pad arranged as a three by three grid with one left over, the order of the numbers, as far as possible, was kept the same.
On a rotary telephone dial the 0 comes adjacent to the 9 because a 0 in the telephone number is signalled by in pulses on the line.
When telephones acquired push buttons in a grid, the ordering of the buttons was carried over from the old telephone dial.
Shamim Ansary:
What Artist Painted With His Tongue?
Huang Erh-nan was a well-known painter who lived in Peking, China, during the 1920s.
Most of his work consisted of ink paintings of butterflies and flowers. But what made Erh-nan’s paintings so amazing was that he painted them not with a brush, but with his tongue!
The Chinese artist filled his mouth with black ink, leaned over a piece of silk cloth, and brushed on his designs using his tongue alone!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version