Introduction (Weather and Climate)

The term weather should not be confused with climate, though they are very closely related to each other in the study of meteorology and climatology. We don’t hear people saying that the climate of the day is warm or cold, but we do talk of warm weather, a cold morning, a sunny afternoon, a rainy day or chilly night. Any casual remarks about the atmospheric conditions of a certain place at a certain time are about weather. Climate means the average atmospheric conditions of an area over considerable time. For climatic averages, a minimum period of 35 years  is desirable.

The Importance of Climate and Weather

The importance of climate and weather can be seen in man’s activities. Forces of nature have regulated to a very great extent the sort of food we eat, what we wear, how we live and work. The direction of winds once controlled the pattern of trading routes. The safety of modern air communications is closely tied to accurate meteorological reports from the ground stations. Despite the advances made in science and technology, farmers and their crops the still at the mercy of the climate and the weather.

A knowledge of the weather of a place will be useful for a farmer to plan his work for the season or the year. Frequent agricultural bulletins issued by meteorological office will assist farmers to take precautions against frosts, hail, heavy snowfall or a period of possible drought sailors at sea are warned promptly of any on-coming gale or typhoon. A fair knowledge of the weather is not only useful but often essential.

The Elements of Weather and Climate

The following elements of climate are normally  observed and measured by weather instruments.

1. Rainfall: Rainfall including other forms of precipitation is always measured by a a metal instrument called a rain gauge. The gauge should be placed at least one foot above the ground and firmly fastened, to avoid splashing. The instrument should be sited well away from tall buildings, high trees and other objects which would shelter it. Rainfall can also be graphically depicted as shaded rainfall. Rainfall can also be graphically depicted as shaded rainfall columns, one for each month of the year.
2. Pressure: Air is made up of a number of mixed gases and has weight, it therefore exerts a pressure on the earth’s surface which varies from place to place and from time to time. This force that presses on the surface of any object can be fairly  accurately measured. The instrument for measuring pressure is barometer.
3. Temperature: Temperature is a very important element of climate and weather. The instrument or measuring temperature id the thermometer.  A temperature taken in open daylight is very high, because it measures the direct insolation of the sun. It is better described as temperature in the sun. Maximum and Minimum temperature are measured by the maximum and minimum thermometers. The Maximum thermometer records the highest temperature reached during the day. The minimum thermometer records the lowest temperature reached during the day, it probably occur in the middle of the night or early in the morning.
4. Humidity: Humidity is a a measure of the damp-ness of the atmosphere which varies greatly from place to place at different times of the day. The actual amount of water vapor present in the air, which is expressed in grams per cubic meter is called the absolute humidity.
5. Winds: Wind is air in motion and has both direction and speed. Unlike other elements in climate such as rain, snow or sleet, winds are made up of a series of gusts that can only be felt but not seen. The instrument widely used for measuring wind direction is a wind vane or weather cock. A direction of wind is always blocked by the trees  and tall buildings, wind vanes need to be erected in an exposed position, to get true direction.

The various climate elements are temperature, precipitation, pressure and winds are the most important because of their far reaching global influences.  These elements and their distribution whether horizontal from equatorial to polar regions, or vertical from ground to atmosphere are in one way or another affected by some or all of the climatic factors i.e. Latitude. altitude, continentality, ocean currents, insolation, prevailing winds, slope and aspect, natural vegetation and soil.