Friday, May 11. 2018What is the mistral?
This is the name given to a wind which blows in the Rhone Valley in France. The wind is caused by an exchange of air between the cold hinterland of France's Central Plateau and the warm Gulf of the Lion in the Mediterranean Sea. High Mountain ranges near flat country produce unpleasant winds, especially where the mountains descend to a warm sea. Atmospheric pressure is high above the cold mountains, but low above the sea. Air, therefore, flows towards the sea and is not warmed because it has not crossed enough land. The north westerly mistral, funneling down the construction of the Rhone Valley, blows at a speed of 30 to 60 m.p.h. on at least 50 days each year. It bursts out on to the Mediterranean coast, filling holidaymakers' caravans with sand and capsizing yachts caught unaware at sea. Picture credit: google Friday, May 11. 2018How are rocks formed?
Sedimentary rocks are formed from the sediment, or broken pieces of the earth's rock structure worn down by weather and erosion. The fragmented pieces become compacted and in time much of it is cemented in to form rock. Igneous rocks originate either from volcanic action as molten lava, which hardens, or from the slow cooling of molten masses beneath the earth's surface, which exposed after a volcanic eruption on or after much erosion. Many important minerals, notably uranium, have been found, enveloped in igneous rocks. The chief sedimentary rocks are sandstone, shale, dolomite and limestone. Picture credit: google 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 |
|
