My Science School

 

The tiny water droplets inside a cloud may bump into each other and join together to form larger droplets. If the air inside a cloud is rising, these droplets are lifted up again and join with others to form yet larger droplets. When the droplets are very large, about the size of raindrops, the rising air can no longer lift the drops back up and so they fall as rain.

 

 

 

 

 

 

 

The water cycle

The evaporation of water caused by sunshine makes the air moist. Moist air travelling inland may have to rise over hills and this cools it. As the rising air is cooled, clouds form and rain may fall. The rain falling on the land runs into streams, which flow into rivers. The river water eventually returns to the sea.

 

Continue reading "RAIN AND SNOW"

 

We usually think of air as being weightless, but in fact air is quite heavy. The air in a large classroom has the same weight as a small car! The air of the Earth’s atmosphere reaches upwards for several hundred kilometres. The effect of this is that the air at ground level presses on everything it surrounds.

The exact air pressure changes from day to day. Studying air pressure, and the way it is changing, helps to tell us how the weather will change in the next few hours and days. Usually, high pressure brings good weather whereas low pressure brings bad weather. A device called a ‘barometer’ measures air pressure and is used to predict the weather.

 

 

 

 

 

On this map you can see areas of high pressure (H) and low pressure (L).

 

 

 

 

 

 

 

The effects of air pressure

You can see an effect of air pressure with a washing-up liquid bottle. If you remove most of the air from inside the bottle, by sucking it, the bottle collapses. This is because the air around it pushes inwards. Normally the air inside balances this force. Simple barometers measure changes in pressure in a similar way.

 

 

 

 

 

 

 

 

Large swirls of cloud like this one often indicate areas of low air pressure.

Weather forecasting is partly done by looking at the movements of ‘fronts’ – regions where warm air meets cooler air. The warm air at a front rises over the cooler air. This cools the warm air and so rain often falls near fronts.

Where warm and cool air meets, the warm air may become partly surrounded by cooler air. As warm air causes lower pressure, this creates a low pressure area called a ‘depression’. When a depression moves over us, we can expect unsettled, rainy or stormy weather.

A high pressure region called an ‘anticyclone’ form where cool air is surrounded by warmer air. An anticyclone moves slowly and can mean a long period of dry or sunny weather.

 

 

 

Bad weather can make driving very dangerous.

 

 

 

 

 

 

Movement of fronts

The region where cold air pushes against a mass of warm air is called a ‘cold front’.

The cold air burrows under the warm air (1) causing it to rise, and so clouds and rain are formed in the rising air.

The cold front catches up with a warm front, where warm air moves into a region of colder air (2). Here, the warm air rises over the cold air, causing more clouds and rain.

Eventually the cold air on the left catches up with the cold air on the right, and the warm air is lifted above ground level (3).

Finally, the warm air disappears, and we just see a region of cool air moving over a region of colder air (4).

 

Sometimes the weather can be extremely violent. One of the most severe types of weather is a hurricane, which may happen near tropical oceans.

Another violent form of weather is a thunderstorm. Thunderstorms happen in extremely moist air, where the grey-black thundercloud stretches up several thousand metres. Inside a thundercloud there are fast air currents which cause ‘static electricity’, electric charge, to build up inside the cloud. Lightning and thunder occur when this electric charge leaps from cloud to cloud or to the ground. The fast air currents inside thunderclouds can hold up large raindrops and so produce very heavy rain.

 

 

 

Thunderstorms can cause bolts of lightning to jump from a cloud to the ground.

 

 

 

 

 

Inside a hurricane

In the centre of a hurricane, called the ‘eye’, there is very little wind. Around the eye, there are very strong winds spiralling round and upwards. Further out there are swirling regions of cloud, reaching perhaps 50 km across. These clouds produce torrential rain.

The most important factor that influences the climate of a place is its distance from the equator – the imaginary line around the centre of the Earth. Places further away from the equator are usually cooler than places that are nearer. This is because the Sun’s light is spread over a larger area towards the Earth’s poles and it has to travel through more of the atmosphere to get there.

 

Climate and the sea

Places far from the sea, or hidden from the sea by great mountain ranges, often have very little rainfall – the air reaching them has already lost most of its moisture as rain on its journey over the land.

Places near to the sea do not usually have great temperature changes. The sea heats up much more slowly than the land and cools more slowly. Therefore, it keeps the land warm in winter and cool in summer.

 

 

 

 

Deserts often have little rainfall because they are sheltered by mountain ranges.

 

 

 

 

 

 

 

 

The climate is affected by how high up you are and where in the world you are. As you go higher, the climate becomes cooler and eventually too cold for trees to grow. Even higher, the ground is covered by snow all year round. The ‘snow line’ and ‘tree line’ become lower as you move away from the equator.

The snow line and the tree line on the side of the mountain.

 

 

As the Earth spins on its axis, it orbits about the Sun. This means that at different times of year, different parts of the world directly face the Sun in the middle of the day. In January, places about 2,000 kilometres south of the equator have the hottest weather. In July, the hottest weather is about 2,000 kilometres north of the equator. This means that the warmest season in the northern parts of the world is during July and in the southern part during January.

Many climates further away from the equator have four seasons. The weather in winter is often too cold for most plants to grow, and there is a good deal of frost. In summer and winter the weather is often stable for longer periods of time. The weather in spring and autumn often changes from day to day, with high winds and sudden showers. The main season of growth is spring.

 

 

 

 

As the hottest regions change, the directions of winds and positions of fronts change around the world. These winds and fronts affect rainfall, and so some regions have distinct rainy and dry seasons. In India, for example, there is a very rainy summer season, called the wet ‘monsoon’, but little or no rain from December to April.

The wet monsoon often causes flooding.

 

Around the world, weather stations record the type of weather every day – they monitor the temperature continuously, the amount of rainfall and the hours of sunshine. Air pressure, which affects the weather, is also recorded. Measuring the ‘humidity’, or amount of moisture in the air, helps to predict clouds, fog or rain.

Satellites can be used in long-range weather forecasting – predicting the weather for a period of weeks. They orbit the Earth photographing it and recording weather patterns. Information sent back to the Earth could include warnings of a fast-developing storm in the tropics, or of a sudden snow melt in a mountainous region.

 

 

 

 

Recording sunshine

A sunshine recorder uses a large round lens to focus the Sun’s rays and burn a mark onto a piece of card. As the Sun moves across the sky, the burn mark leaves a trail showing how long the Sun has been shining.

 

 

 

 

 

 

The weather satellite Tiros orbits the Earth recording the weather.

Most people like to know in advance what the weather will be like. Weather forecasters often look for signs of fronts approaching – as a warm front approaches, the air pressure decreases and as a cold front approaches the air pressure increases. These changes in pressure often bring rain. A steady area of high pressure often says we can expect dry weather, cold in winter, warm in summer. Professional weather forecasters may use radar to watch how the clouds are moving. Information can also be processed by a computer to show, for example, temperature differences.

 

 

 

Satellite images can show a storm developing.

 

 

 

 

 

 

 

Pine cones are also a tool for the amateur weather forecaster. When the air is moist, just before rainfall, pine cones close their scales. In dry weather, the scales open again.

 

 

 

 

 

 

Many well-known sayings help amateur weather forecasters to predict the weather. “Red sky at night, shepherds delight”, says that a red sunset will bring dry and warm weather.

 

 

 

The fluffy, white clouds you see on fine, summer days are called ‘cumulus’ clouds. When these rise up to form dark ‘cumulo-nimbus’ thunderclouds, there is a good chance of a heavy shower or a thunderstorm.

‘Cirrus’ clouds are the thin, wispy clouds you sometimes see very high in the sky on dry days. They usually mean a front is arriving, so you can expect the weather to change. As a front moves nearer, the cloud gets lower, turning into ‘alto-stratus’ or small ‘alto-cumulus’. Tall heaps of alto-cumulus means there may be a storm. Lower down, grey ‘nimbo-stratus’ clouds often cause continuous rain. ‘Stratus’ clouds form as a low sheet and often cause fog.

Samir Kumar Brahmachari (born 1 January 1952) is an Indian biophysicist and Former Director General of the Council of Scientific & Industrial Research (CSIR) and Former Secretary, Department of Scientific and Industrial Research (DSIR), Government of India. He is the Founder Director of Institute of Genomics and Integrative Biology (IGIB), New Delhi and the Chief Mentor of Open Source for Drug Discovery (OSDD) Project. He is the recipient of J.C Bose Fellowship Award, DST (2012).

Fields

• Functional Genomics;Structural & Computational Biology

Known for

• Open Source Drug Discovery for Affordable


• Healthcare

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Satyendra Nath Bose, FRS (Bengali: Sôtyendronath Bosu; 1 January 1894 – 4 February 1974) was an Indian physicist from Bengal specialising in theoretical physics. He is best known for his work on quantum mechanics in the early 1920s, providing the foundation for Bose–Einstein statistics and the theory of the Bose–Einstein condensate. A Fellow of the Royal Society, he was awarded India's second highest civilian award, the Padma Vibhushan in 1954 by the Government of India.

Known for

• Bose–Einstein condensate


• Bose–Einstein statistics


• Bose–Einstein distribution


• Bose–Einstein correlations


• Bose gas


• Boson


• Ideal Bose Equation of State


• Photon gas

Awards

• Padma Vibhushan


• Fellow of the Royal Society

Fields

• Physics

To know more Click Satyendra Nath Bose 

Raghunath Anant Mashelkar, also known as Ramesh Mashelkar. FREng, FIChemE (born on 1st January, 1943) is an Indian chemical engineer and a former Director General of the Council of Scientific & Industrial Research (CSIR), a chain of 38 publicly funded industrial research and development institutions in India.

Awards

• Padma Vibhushan


• Padma Bhushan


• Shanti Swarup Bhatnagar


• G.D. Birla Award for Scientific Research


• FREng

Fields

• Chemical Engineering

Known for

• Intellectual Property Rights; R&D; Innovation

For more details about Raghunath Anant Mashelkar

Nitya Anand (born 1 January 1925 in Layallpur, British India) is a scientist who was the director of Central Drug Research Institute in Lucknow for several years. In 2005, Indian Pharmacopoeia Commission (IPC) appointed him chairman of its scientific committee. In 2012, he was awarded the Padma Shri by the Indian government.

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Ganapathi Thanikaimoni (1 January 1938 – 5 September 1986), often referred to as Thani was an Indian palynologist.

Known for

• Contributions to the science of palynology

Scientific career

Thani took a position of scientist in the newly founded (1960) Palynology Laboratory of the French Institute of Pondicherry (French: Institut Français de Pondichéry) under the direction of Dr. Prof. Guinet. In a few years Thani's scientific and administrative abilities were recognized by his promotion to the directorship of the laboratory.

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Biman Bagchi (born in 1954) is an Indian biophysical chemist, theoretical chemist and an Amrut Mody Professor at the Solid State and Structural Chemistry Unit of the Indian Institute of Science. He is known for his studies on statistical mechanics; particularly in the study of phase transition and nucleation, solvation dynamics, mode-coupling theory of electrolyte transport, dynamics of biological macromolecules (proteins, DNA etc.), protein folding, enzyme kinetics, supercooled liquids and protein hydration layer.

Known for

• Statistical Mechanics


• Solvation Dynamics


• Biological Water


• Mode Coupling Theory

Awards

• 1986 INSA Medal for Young Scientists


• 1990 INSA A. K. Bose Memorial Medal


• 1991 Shanti Swarup Bhatnagar Prize


• 1997 G. D. Birla Award


• 1998 TWAS Prize


• 2002 Indian Institute of Science Alumni Excellence Award


• 2003 Goyal Prize in Chemistry

Fields

• Biophysical Chemistry


• Theoretical Chemistry


• Statistical Mechanics

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