Monthly Archives: March 2014

43.WHY DO WE HAVE FLOODS?

For as far back as we can go in the history of man, we find records or tales, or legends, about great floods. The reason for this is that there have always been floods. In fact, primitive man deliberately settled in the valleys that were in the paths of floods because they were so fertile.

What is a flood? It’s a condition that exists when a river overflows its banks and the water spreads out elsewhere What causes a flood? the accumulation of a great deal of water in a river that comes from heavy rains, or from other streams or reservoirs that feed into the river. A river usually drains a vast area, or ‘watershed,’ and it is the heavy flow of water from anywhere in this watershed that makes a river rise and flood over its banks.

42.WHERE DOES WATER GO WHEN IT DRIES UP?

You look out on the street or road and you see water. An hour later in bright sunshine, it is gone! Or wet clothes are hung out on a line, and by the end of the day, they are dry. Where did the water go?

We say the water evaporates. But what does this mean? Evaporation is the process by which a liquid that is exposed to air gradually becomes a gas or vapor. Many liquids evaporate quite quickly, much more quickly than water. This is true of alcohol, gasoline, and ammonia. Some liquids, such as mercury, evaporate very slowly.

41.WHAT WOULD HAPPEN WHEN THERE IS NO DUST?

Would the world really be so much better off if there were no dust? The answer is: in some ways—yes; in some ways—no. What is dust, anyway? It consists of particles of earth, or other solid matter, which are light enough to be raised and carried by the wind. Where do these particles come from? They might come from dead plant and animal matter, from sea salt, from desert or volcanic sand, and from ashes or soot.

For the most part, dust is not a very desirable or beneficial thing. But in one way, it helps make the world more beautiful! The lovely colors of the dawn and of twilight depend to a great extent on the amount of dust that is present in the air.