Ask Mr Brain...all will be explained

PUBLISHED : Monday, 31 January, 2000, 12:00am
UPDATED : Monday, 31 January, 2000, 12:00am

Is it true that it will get warmer when it snows? Snow does not cause the warmth, it is the warmth that causes the snow. The atmosphere needs to warm up (relatively speaking) before snow can start to fall. During very cold weather, the capacity of the air to hold moisture is greatly reduced. The water vapour that remains is deposited as frost. At the same time, evaporation is reduced, leaving air humidity very low. Snow cannot form in these conditions.

Warmer air can hold more moisture before saturation point is reached and the water vapour begins to condense out. So when warmer air moves into cooler areas, not only do we feel the increase in temperature but the excess vapour precipitates as snow.

Why do batteries run down faster in cold weather? Electric current is produced by a battery when a connection is made between the positive and negative terminals of a piece of electrical equipment. The current is the result of a chemical reaction in the battery, and such reactions proceed more slowly at low temperatures.

If a battery is used at a low temperature, less current is produced than at a higher temperature. So batteries more quickly reach the point at which they cannot deliver enough current. If the battery were exposed to a higher temperature again, it would usually operate without any problems.

Why do hammerhead sharks have such strange heads? The reason for this is unknown, but several suggestions have been put forward as to why hammerhead sharks and their cousins, the bonnetheads, have evolved in this way. It is possible that the 'wings' that jut out on either side of the shark's head to create the hammer shape act as hydrofoils, aiding its movement and adding extra lift. This enables the shark to bank and make vertical movements more quickly.

Secondly, the eyes of a hammerhead are at either ends of these wings and this could enhance the shark's binocular vision, allowing it to judge distance more accurately.

There are also reports that hammerhead sharks use their heads to 'hammer' and pin down stingrays, their favourite food.