Weather and Climate

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Weather and Climate

Weather is the daily condition of the atmosphere measured over a short period of time.

Climate is the average weather condition measured over a long period of time.

There are positive and negative effects of weather which include:

Positive - solar energy, wind energy, games, agriculture (rain), tourist attraction

Negative - floods claiming lives, drought, famine, ruin of plans (delay flights), destroy roads

Yet we find that weather is different in different places around the Earth. This is because of the following:

The tilt of the Earth at 23.5 degrees

The latitude of the place(s) which is the distance away from the Equator

The altitude of the place(s) which is the height above sea level

Ocean currents which include warm or cold currents

Relief which is the structure of the land or place(s)

The winds blowing

Weather comes in many forms; precipitation (water vapor), humidity, temperature, wind, sunshine etc, are forms of weather or weather elements.

They can be measured through various instruments.

Temperature:

The term "temperature" means how hot or cold it is and is generally measured using a Six's thermometer in degrees Celsius. The Six's thermometer is also known as the maximum and minimum thermometer.

Features of the Max/Min thermometer:

Though it is not shown in the diagram below a Six's thermometer does have a magnet at the bottom in the center to reset the thermometer after taking readings.

The metal index/indices are to indicate the maximum and minimum temperature of the day.

The mercury is used in measurement of temperature because it is sensitive to slight changes in temperature.

The vacuum at the top allows easy expansion and contraction of alcohol and mercury.

How to read the Max/Min thermometer:

The temperature must first be reset through help from the magnet which will then position the metal indexes on the top of the mercury. While the max temp is recorded from the right column, the min temp is recorded from the left column and is read at the bottom of the metal index. When the temperature rises the mercury expands, pushing the metal index to indicate the max temp on the max scale. When the temperature drops the alcohol contracts, pulling the metal index down to indicate min temp on the min scale. Therefore giving a range of temperatures. The present temp is read right where the mercury ends and is the same on both scales

The Diurnal temperature is the Daily temperature. The Max/Min thermometer is kept in the Stevenson's screen to allow the Six's thermometer to measure temperature of the air (room temperature)

Below is a diagram of a Six's thermometer. Most of these thermometers tend to have a magnet at the bottom right in the center of the 'U' though it is not shown in the diagram.

Rainfall:

The term "rainfall" means the quantity of rain falling within a given area in a given time that is measured using a rain gauge in millimeters (mm). Rainfall occurs when water vapor condenses forming clouds and then giving off precipitation in form of rain.

Clouds form when the Sun's energy evaporates water from water bodies, land and trees (transpiration), the warm air rices and condenses to form clouds that then give out precipitation. Clouds are made from water droplets.

There are 3 types of rainfall: convectional, relief and frontal.

Convectional rainfall is when the air rises because the ground heats it. It rises in warm currents called convection currents thus the name convectional rainfall. The diagram below shows this:

Relief rainfall is when the wind meets a line of high hills or mountains the wind can only go up so the air rises and cools and thus giving us relief rainfall. The diagram below shows this:

Frontal rainfall is when a warm air mass meets a cold one forcing the warm air to rise thus giving us frontal rainfall. The diagram below shows this:

A rain gauge, used to measure precipitation (rain) is put in the ground but there must be 30 cm or more above the ground. After 24 hours or one day you take the rain gauge out of the ground and pull the funnel . Once you pour the collected water from the jar into a measuring cylinder, take readings at eye level at the same time daily in millimeters. Taking readings at the same time makes the results more accurate (no exaggeration).

Features of a rain gauge:

Funnel - directs rain droplets to the jar

Jar - collects rain water

30 cm - so water doesn't splash back into the jar

Rain gauge site:

The best site for a rain gauge would be on flat ground with short grass and no trees or any sort of obstruction above. This is because on flat ground the run off water will not wash off the rain gauge and with the short grass there won't be much back splash. If there is any obstruction above then water will either not reach the rain gauge or the water dripping from the obstruction will collect into the gauge which won't give accurate results.

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