• HEAT WAVES •
A heat wave is defined as a prolonged period of excessively hot weather, which may be accompanied by excessive humidity and no rains. The term is relative in nature. For example, the temperature considered normal or even below normal in one region can be called a heat wave in a cooler area. Thus, the term heat wave is applied not only to extraordinary spells of heat which may only occur once a century but also routine weather variations. To be a termed as a "heat wave" such a period should last at least three days, but conventionally it lasts from several days to several weeks and may extend to even months.
In temperate climates, a heat wave is only with temperatures of 30 °C (86 °F) or more. However, in countries such as Australia where 30 °C is considered mild on a summer day, heat waves are far more dangerous. For example, In early 2006 in Adelaide in Southern Australia, was hit by a heat wave with temperatures ranging 40+ °C for five days in a row, while some regions of the country experienced temperatures hovering around about mid 40s°C with one day recorded even 48 °C. On the other hand, the temperature regularly touches 40°C in the summer months of Northern India.
Another important term associated with heat waves is “heat index” which is the apparent temperature that describes the combined effect of high air temperature and high humidity. The higher this combination, the more difficult it is for the region to cool itself.
Heat waves have vital effects on the region. With enormous loss of lives to diminishing quality of crops and cattle, heat waves not only disturb the physical lives of the people and their economy but also leave mark on the climate and temperature of the region, causing an ecological imbalance. Heat waves can also cause droughts as well as massive wild fires.
Human bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and-as the last extremity is reached-by panting, when blood is heated above 98.6 degrees. The heart begins to pump more blood, blood vessels dilate to accommodate the increased flow, and the bundles of tiny capillaries threading through the upper layers of skin are put into operation. The body’s blood is circulated closer to the skin’s surface, and excess heat drains off into the cooler atmosphere. At the same time, water diffuses through the skin as perspiration. The skin handles about 90 percent of the body’s heat dissipating function.
Heat waves can seriously affect the human body. They can cause-
SUNBURNS: Sunburns cause redness and pain. In severe cases swelling of skin, blisters, fever and headache can occur.
HEAT CRAMPS: Heat cramps produce painful spasms, usually in muscles of legs and sometimes the abdomen with heavy sweating all over the body.
HEAT EXHAUSTION: Heat exhaustion can cause heavy sweating, weakness, paleness and clamminess in the skin sometimes accompanied by fainting and vomiting.
To sum up we can say-
“Heat waves are those times,
Which, take their revenge for all our crimes.
So hot it is! We always complain,
Why this happens? Only the earth can explain.”