Wednesday, May 9. 2018Why do clouds have different shapes?
Clouds vary in shape according to their height and temperature, and they contain minute drops of water or ice particles or a combination of both. And, of course, their formation is greatly affected by wind changes. There are basically three groups of clouds: high clouds between 17,000 and, 45,000 feet (cirrus, cirro-cumulus' and cirro-stratus); middle clouds between 7,000 and 23,000 feet (alto-cumulus, altostratus and nimbo-stratus); and low clouds up to 7,000 feet (stratocumulus, stratus, cumulus and cumulo-nimbus. Their height and temperature decide how much pressure is exerted on them by the atmosphere. Finally, the shapes of clouds differ according to the time of day. Towards evening Clouds tend to thin out, rise a little and flatten out. Picture credit: google Wednesday, May 9. 2018What is the date line?
The Date Line (usually called the International Date Line), is a north-south line through the Pacific Ocean where, according to international agreement, the date changes. East of the Line it is one day earlier than it is to the west. The line is necessary because the earth is divided, longitudinally, into 24 one-hour time zones (15° longitude each) which make one full day on the earth. Since the earth rotates eastwards, the time on the clock progresses westward, round the world. Thus, 12 o'clock noon arrives in London (0° longitude) five hours before it does in Washington, D.C. (75° west of London) and eight hours before it does at San Francisco (120° west of London). When it is noon in London it is midnight 180° to the west. On either side of the 180th meridian the time is the same. But you would lose a day if you crossed it from the east and gain one if you travelled across it from the west. The Date Line has some variations from the 180th meridian to allow for land areas or islands. The line bulges eastwards through Bering Strait to Take in eastern Siberia and then westward to include the Aleutian Islands with Alaska. South of the equator bulges east again to allow various island groups to have the same day as New Zealand. Picture credit: google Wednesday, May 9. 2018Where do Icebergs go?
Icebergs are huge masses of ice which have broken away from glaciers in the Arctic and Antarctic regions. They gradually melt away as the upper part is warmed by the sun and the lower part by the warmer waters into which they drift. An iceberg may be as much as 250 feet high, although only one ninth is above the surface of the sea. It can be a hazard to shipping. The worst disaster was to a British passenger liner, the Titanic. This fine ship was thought to be unsinkable, because she had a double skin and 15 watertight compartments. In April, 1912, the liner struck an iceberg in the North Atlantic. Despite her double skin and watertight compartments she was holed and quickly sank. Of the 2,207 people on board, more than 1,500 were drowned. Picture credit: google |
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