COLUMN: IN THE WILD. This is how weather impacts life in the Savannah

FROM the southern highlands, central, coastal regions to the northern zone chorus from frogs before and during the rainy season is a clear indication to farmers of enough rain in that particular season of a year.

One may wonder how these small animals are capable to do this complicated process and come up with clear results. Frogs can sense chemical changes in the air, not just from the nostril but from molecules collected on their eyes and skin.

Scientists define weather as an atmosphere at a place at given time. Weather is measured and recorded over a short period of time, like within an hour, day, month or a year in a given area.

Weather changes from place to place and from time to time. A day can be hot, cold, rainy, cloudy, dry, windy or sunny.

Weather enable people to plan for their different economic activities. It enables people the occurrence of a certain season at a given time in a year. Weather has a great influence in the day to day human activities because when it is dry, pastoralists move with their animals from one place to another to seek water and pasture for their animals. When it is very cold, people in the cold temperate regions migrate to the warmer regions.

This may lead to tourism in those areas they move to. Abundant rainfall encourages agricultural activities to be carried out. Heavy rainfall may destroy people`s property, agriculture activities, infrastructure, as well as preventing people from going to their places of work.

Fishermen are able to the movement of fish from one place to another, thus facilitating fishing activities. Meanwhile scientists say a wind is air in motion that blows from the area of high-pressure belt to low pressure belt. Wind can be grouped into two main types, namely local wind and pressure belt.

Local winds are those which occurs regularly or periodically, and blow for a short time and affect a small area of the earth’s surface. Examples of local winds include land breeze, sea breeze, and mountain wind. Sea breeze refers to the wind that blows from the sea to the land during the day.

During the sea to the land heats up quickly than the sea and becomes warmer than the sea, and the air pressure on the land is lower than that of the sea, Therefore, wind blows from the sea to the land. Land breeze refers to the wind blowing from the land to the sea during the night. During the night, the land cools quickly than the sea therefore low pressure develops on the sea.

Rain refers to the droplets of water falling from the atmosphere after condensation process has taken place. When water vapor rises, it cools at high altitude until dew point is reached.

Dew point is the temperature at which the atmosphere is saturated with water vapor. Condensation takes pales after dew point has been reached to from water droplets. These droplets combine to form larger drops which fall as sun.

There are three types of rainfall and Convectional rainfall is formed through vertical of moist air currents. Convectional currents rise due to differential heating of the earth’s surface.

Convectional is common in East Africa, around Lake Victoria. The risen air later condenses and fall back as rain. In some streets of Mwanza town like Makoroboi people call these beautiful lizards Gongamawe because of the habit of nodding their heads.

The Sukuma also use Gomomhole for the Agama Lizards because they believe that the reptile will nod its head even when climbing on top of an Elephant regardless of difference in size.

Enyangala is the name for Agama lizards among the Waikuzu of Bunda while Sukuma people of Mwanza and Shinyanga call these fast moving lizards Zare. Unlike the Sukuma, in Mara the Wanata, Waikoma and Wangureme people of Serengeti believe that the red headed agama lizard has magical power of deterring thunder and lightning from heating them.

Scientists say it’s the male agama lizard who have bright colors which they use to attract female during breeding season.

Agama Lizards are active in early hours break at noon and come out in the afternoon hours because they can’t tolerate high temperatures, so to see them please observe their schedules. Every day there hundreds if not thousands of these lizards roaming on rocks standing around lake Victoria.

Scientists say rainfall is one of different stages of a big hydrological cycle which also called H2O cycle that allow water in different forms to rotate in and around the planet earth.

This process enable liquid water from different sources inside tropical rainforests to flow through streams which forms big rivers such as Ruvu, Wami, Pangani, Ruvuma, Malagarasi and Rufiji that pour all their contents into Indian ocean every year from 150 million years ago.

This become more significant when big lakes such as Victoria, Tanganyika and Nyasa join hands with other bigger water bodies on earth such as Pacific, Atlantic and Indian ocean to make 361.132 square kilometers which occupy 70.08% of the total area of planet earth.

Due to this size, scientists estimate that all water bodies around the world harbor more than 230,000 marine species were crocodile and hippopotamus are found around river and lakes, sharks, dolphins and whales dwell in different sea and oceans of the world.

With about 1.3 billion cubic kilometers of water, streams, rivers, lakes, seas and oceans play a big of preserving water in liquid form for longer period than any parts in and around the planet Earth. Scientists estimate before evaporating into the sky one liter of water spend more than 3,200 years moving from one part to another inside large water bodies such as Pacific, Atlantic and Indian ocean but this period lasts up to more than 20,000 years in Antarctic and Arctic.

While depending on supply from different streams and rivers, big lakes such as Victoria, Tanganyika and Nyasa are capable of preserving one liter of water for a period which lasts between 50 to 100 years before it is discharged into the sea through big rivers such Nile which empty its content into Mediterranean sea.

Unlike streams and rivers such as Wami, Ruaha and Rufiji which pass under forest canopies, the rate of evaporation on lakes, seas and oceans is bigger because of large surface which exposed to sunrays from the sky.

Hot sunrays hit water on the surface of a lake and heat its molecules into a boiling point where they are transformed into vapors which through a process called evaporation escape into the sky where they form rainy clouds.

Different factors affect this process but the number of molecules and good amount of oxygen in a single drop of water on the surface of a water body play an important role in evaporation on big lake such as Victoria, Tanganyika and Nyasa.

When rate of fresh air that enter into a water body become bigger it accelerate the rate of evaporation on the surface of a lake or ocean, while gravitation force which upon molecules may bring down the rate of evaporation on the surface water.

At a long process of the big hydrological cycle, the evaporation stage plays a crucial role to purify water before sending it to the sky where it stay in form of clouds before it turns into rain which nourish lives of animals, birds, insects and vegetation on the earth.

At the same time scientists say about 20% of all amount of water that is available on the earth accumulate on the Aquifer, this is an underground storage which receive water through infiltration on porous underground rock and accumulate one big area.

The upper part of an Aquifer is called water table as scientists say the precious liquid may be stored into this underground storage for a period which lasts between 100 to 10,000 years before coming out through underground stream and springs.

After a rain season, good amount of rain water accumulate on valleys, flood plains and other wetlands which become source of water for different animals in different national parks and game reserve such as Selouse and Moyowosi.

Scientists estimate that all these reservoirs may store water for a period which lasts for more than three months while providing water for buffaloes of Katavi national and quenching thirsty Gerenuk, Oryx and other animals in Mkomazi national park at the time when there is no rain.

Through the same process of hydrological cycle, water from these storages allow water go through evaporation and escape into sky as vapor while between 1% and 0.5 % all surface water is used by different plants through their roots. During dry season through a process called transpiration plants allow 99% of water which go into the sky in the form of vapor from stomata which their numbers on a leaf affect the rate of evaporation from that particular plant.

Temperature also affects the rate of evaporation from a leaf because during dry season stomata are opened frequently forcing different vegetation in a hector inside Tarangire national park to lose about 11,400 liters of vapor a day while large trees lose 151,000 liters or 40,000 gallons of vapor in a year.

Speed and rate of hydrological cycle on big water bodies is fast and large because of shape and numbers of molecules in water on the surface of a lake, sea and ocean is good for attaining boiling point without the presence of fire.

On other side, relief rainfall is formed when the moisture laden wind is forced to rise over a mountain. When the moisture-laden wind reaches higher altitude, the moisture condenses to from droplets, which fall as rain. Rain formed in this way is also called orographic rainfall.

The side of the mountain receiving the rain is known as the windward side. That side which faces away from the direction of the wind is known as the leeward side or the rain shadow. The leeward side gets very little rain.

A go example of a rain shadow in Tanzania is found on the western side of Mount Kilimanjaro. Wind-blown from the Indian Ocean in the East is forced by this mountain to rise and drop most of the moisture on the eastern and south eastern slopes.

When these winds blow over to the western side of the mountain, the winds are already relatively dry. Relief rainfall falls in light showers.

It rarely falls in lowland areas. Standing 8,848 meters above sea level, the of Everest on Himalaya mounts is the tallest natural structure while at 5,895 meters above sea level, Kilimanjaro is the tallest free standing mountain on Earth.

Unlike the peak of Everest which is built above more than hundred mountains, Kilimanjaro is tallest free standing mountain in the world towering to the African sky alone.

The Himalayas ranges of mountains covers an area of about 147,181 square kilometers, miraculously from a base covering not more than 40 square kilometer Kilimanjaro pop up from the surrounding plains.

The Himalayas alone contains nine of ten tallest mountains in the worlds while from the Maasai plains, Kilimanjaro is neighbors mount Meru which one tallest mountains in Africa.

From the side of mount Meru, Ngurdoto crater lays about 1,491 meters above the sea level almost on the same elevation with Kiraacha village on the slopes of mount Kilimanjaro Located in the middle of banana forest, Kiraacha is found between 1,600 and 1,800 meters above sea level where its villagers are known to utilize the elevation on their advantage.

The village is characterized by lower temperature throughout a year, this is good situation which allow some clever villagers to preserve different food stuffs underneath streams with cold water from the mountain. It is said that a house wife of Kiraacha village may wrap five kilograms of meat and with confidence may store them on the ground for many weeks just like her counterpart in Upanga use a deep freezer.

Meanwhile cyclonic rainfall is formed when large masses of air with different temperatures and moisture meet. As the warm and moist air is forced up over the cools and dry air, it expands. At higher altitude, the warm air cools and water vapor condenses to could that later fall as rain.

The writer can be reached via: rstanslaus@yahoo.com