Category The Earth, Earth Science, Planet Earth

CLIMATE

Different parts of the globe have very different climates. It gets hotter as you travel towards the equator because the Sun’s rays are more concentrated there. Places near the sea are usually cooler in summer and warmer in winter, than places inland. This is because the sea heats up and cools down less easily than the land, and so keeps the land near the sea warm in winter and cool in summer.

These differences in temperature cause movements of air across the Earth’s surface, called winds. Air movements, in turn, cause clouds and rain to form, as warm, moist air is cooled by rising up over hills.

 

 

 

The Sun’s rays travel about 150 million km to reach the Earth, providing our planet with light and heat. By rotating once every 24 hours, the Earth keeps the distribution of heat and light balanced with regular alternating periods of daylight and darkness.

The Sun’s rays fall at both the equator and the poles. At the equator, the Sun’s rays are spread over a smaller area than rays reaching the Earth at the poles. This means that sunlight reaching Polar Regions is less intense than sunlight reaching the equator. It also means that places near the poles are colder than places near the equator.

 

 

 

 

 

Temperatures drop considerably at the two poles, which are mainly covered in snow and ice.

 

 

 

 

 

 

 

The hottest and driest climates on Earth are found in the deserts.

 

 

THE ATMOSPHERE

 

 

 

 

The air you breathe forms a thin layer – the ‘atmosphere’ – around the Earth. This stretches up for a few hundred kilometres. As you go higher, there is less air. At the height where planes fly, there is too little air to breathe.

Most plants and animals need atmospheric gases in order to live. Animals rely on ‘oxygen’ to breathe and plants rely on ‘carbon dioxide’ to make their food. The air also contains nitrogen, small amounts of other gases, and some water vapour and dust. The ‘stratosphere’ and ‘ionosphere’ contain small amounts of ‘ozone’, which is a form of oxygen. A layer of ozone prevents harmful ultraviolet rays from the Sun reaching the Earth’s surface.

 

 

 

 

 

 

 

The aurora is caused by charged particles from the Sun hitting the atmosphere.

 

 

 

 

 

 

 

Exosphere

The highest, outer region of the Earth’s atmosphere is called the ‘exosphere’. Here, conditions are not very different from outer space as there is only very little air indeed.

Ionosphere

The ‘ionosphere’ is made up of electrically charged particles produced when radiation from the Sun hits the upper atmosphere. Near the poles, this causes a brilliant display of lights, the ‘aurora’.

Man-made pollution is now causing a hole to appear in the ozone layer.

Stratosphere

The ‘stratosphere’ extends up to about 80 km above Earth. As you travel upwards in this layer, the temperature rises slightly; nevertheless temperatures are below freezing point.

Troposphere

The ‘troposphere’ contains the air we breathe. Clouds rain and snow all form in this layer. As you travel up through the troposphere, it becomes colder.

EARTH’S BALANCE

The parts of the world affecting our lives are called the ‘environment’. This includes the Earth’s crust, oceans, atmosphere, plants and animals. If the balance between things added and things taken away from the environment is upset, the environment will change.

Many of the things we take from the Earth, like metals and fossil fuels, take millions of years to be replaced naturally. Other things, like wood from trees, are replaced more quickly, but if we use them too fast, they will disappear. Some things we produce, like poisons and waste, are not removed as quickly as we add them to the environment, so they build up as pollution.

Household waste is a serious pollution threat – the UK produces 27 million tonnes each year.

 

 

 

 

Cutting down huge forests can cause changes in the Earth’s atmosphere.

 

 

 

 

 

 

Pollution from industry can also disturb the Earth’s balance.

MORE ABOUT PLANET EARTH

Moving Crust

As the plates of the Earth’s surface move towards each other, one plate may rise over the other one. The one which goes up forms mountains and the one which goes down is slowly melted below the Earth’s surface. Where two plates move away from each other, magma is free to escape. It solidifies to form rock, and a ‘mid ocean ridge’ or a ‘volcanic island’ is formed.

 

 

 

Folding

Movements in the Earth’s plates can also cause the Earth’s surface to buckle and split. Where the surface splits and slips, a ‘fault’ is produced. Where the surface buckles, a ‘fold’ is formed. Many familiar features of the landscape are caused by folds and faults, and these can often be seen in layers of rocks at seaside cliffs. The diagram shows some of the features that can be produced in these ways.

 

How can we use the internal heat of Earth?

               We know that our Earth is ball-shaped. If we continue digging at a particular place, we would notice that the temperature goes on increasing with the increase in depth. Before we discuss the subject we must have an idea about the three main layers of Earth. The top, the second and the third. The top or first layer of Earth is a thin crust of hard rocks that floats on the second thicker layer of rock called “mantle”. This is so hot that most of its rocks are partly melted. The third layer is made of hot liquid iron. In fact, at the core it is extremely hot. The temperature can be imagined from the huge amount of energy which is released when the volcanoes erupt.

               Around the year 1800 some Italian scientists performed certain experiments, to make use of Earth’s internal heat. They dug a hole in the earth through which jets of hot steam and pungent gases shot out. These blow-holes are a sign of volcanic activity taking place under the ground. The gases they release into the air come from molten rocks known as magma which lies at depths ranging between 20,000 and 80,000 metres or more.

               Scientists found boric acid in these vents. An industry was set up to extract this chemical substance in Italy in 1818. Later it was discovered that the power of these gas jets could be harnessed for other tasks, including the generation of electricity. For the first time geothermal electricity was generated at Landarello in Italy in 1904.

               The internal heat can be used to produce electric power in four ways: dry steam, as at Landarello; hot water as at Reykjavik, in Iceland; low temperature areas in basins of sedimentary rocks, containing water between 40°C and 100°C which is used for agricultural purposes such as heating glass houses; and high pressure zones found by petroleum drilling deep in sedimentary basins. The natural gas released from the earth in particular localities (generally near deposits of mineral oil) is used as fuel and also as a source of energy.

               In the last few years the scientists have developed several mechanisms for the optimum use of Earth’s internal heat. They have been trying further to develop such instruments further that could be used to utilize the earth’s geothermal energy effectively.

 

The Earth

 

 

What is the Diamond Ring effect?

Just before the Moon covers the Sun completely or just after the Moon uncovers the Sun during a total solar eclipse, a tiny portion of the Sun’s bright disc becomes visible on the Moon’s dark disc, giving an impression of a ring with a brilliant diamond on it.

 

 

 

 

 

What is node?

The Moon’s orbit is inclined at an angle of about 50 relative to the Earth. The monthly path of the Moon and the ecliptic are imagined to be two hoops hinged along a diameter and slightly displaced at an angle to each other, and then the hinges will represent the points of intersection known as nodes.

 

 

 

 

 

How does a lunar eclipse occur?

A lunar eclipse occurs when the Moon enters the shadow of the Earth and when the Earth comes between the Sun and the Moon. 

What is the relation between the phase of the Moon and a lunar eclipse?

When the Earth comes between the Sun and the Moon during a Full Moon, a lunar eclipse occurs if all the three bodies are in a line.