You can easily find the direction of the wind by looking up top see the direction in which the clouds move, or the direction in which the smoke from a chimney travels or a flag flutters.
However the instruments particularly used to find the direction of the wind is the weathercock or wind vane. The wind vane is made up of two parts. On the top is an arrow or vane, which moves freely with the prevailing wind. The other stationary part, with its four compass points shows the direction in which the wind is blowing. Most weather vanes are plac4ed on high buildings so that there is no obstruction in its way for it to correctly indicate the wind direction.
Wind speed
The speed of wind is usually measured by an anemometer. It consists of three or four semicircular cups attached to the ends of horizontal spokes mounted on a high vertical mast. As the concave sides of the cups offer resistance to the winds, the horizontal spokes rotate-moving the central rod. This sends the speed of the wind (in km per hour) to9 an electrically operated dials.
But the speed recorded may not be totally accurate as the cups do not stop rotating even when the gust of wind has passed way.
Rain
Your wife leaves washing out in the sun to dry. If you leave a saucer of water out in the open the water gradually disappears. We say that the water has evaporated. The heat of the sun has turned the water into water vapor. When the sun is very hot, evaporation is faster.
The moist air expands and rises, and cools when the cooling reaches a certain point, the water vapor changes to drops of water. We call this condensation of water vapor. These drops collect around dust or smoke particles or changed air molecules. They remain suspended in the air and float as clouds.
Look at the sky. On different days you see different kinds of clouds. Some are high, some are low wile some are white and some are dark in color. The type of could we are interested in is the dark, low cloud, which is called the nimbus cloud. This type of cloud brings us rain.
Clouds contain moisture. Warm air can hold large amounts of water vapor. Cold air hold only smaller amounts of water. So when warm air is cooled, the water vapor condenses into tiny droplets to form clouds high in the sky. These clouds grow bigger and bigger and when they move into a very cold area, all the tiny droplets condense into bigger drops and eventually there is rainfall.
How is rainfall measured?
Rainfall is measured by a metal instrument called a rain-gauge. The gauge itself is made up of a metal cylinder which has a close fitting funnel. The funnel collects the rain water and sends it into a receiving bottle.
The rainfall is measured by removing the funnel and pouring the water collected into a measuring glass. The glass is graduated in millimeters. The area at the base of the glass is `V’ shaped so that the smallest amount of water collected can be measured. The recording for a rain-day is reckoned as a period of 24 hours and quite often the reading is taken at 8 am. The daily reading are added together to make up the rainfall of the month.
The difference between weather and climate
The terms weather and climate should not be confused with each other though they are closely related. Weather is a general term for conditions, especially in the layer near the ground, at a specific time, ay any one place. These conditions do not remain constant. The temperature, the winds that blow and the amount of rain that falls up the weather of a place.
When we speak of climate we mean the average weather condition over a considerable period of time.