How Earthquakes Happen
Earthquake is one of the most destroying natural disasters. Unluckily it often happens in several regions. Recently a horrible earthquake has shaken West Sumatra. It has brought great damages. Why did it occur? Do you know how an earthquake happens?
Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves. It make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs.
During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus is called the epicenter of the earthquake.
How a cell phone works
A cell phone is a great gadget in this modern world. What is a cell phone? A cell phone is actually a radio in certain way. Like a radio, by a cell phone we can communicate to other people in real time. Million people use cell phone for their communication. Even nowadays, people use cell phones to communicate in voice, written and data. Alexander Graham Bell is the person who make great change in the way people communicate to each other. He invented a telephone in 1876. While wireless radio was formally known in 18994 presented by Guglielmo Marconi. By these two technologies, then a cell phone was born. However do you know how actually cell phones work?
This short explanation on how a cell phone work is really wonderful. A cell phone or in long term "cellular telephone' works by transmitting signals of radio to towers of cellular. The towers are networked to a central switching station. The connection usually uses wire, fiber optic-cables, or microwave.
Then the central switching station which handles calls in certain given area is directed connected to the wire-based telephone system. Cellulars are pick up by the towers and relayed to another cellular telephone user or the user of wire-based telephone network.
The towers vary in the capacity and capability to receive signals. Some can receive the signal from short distance and the others can receive more distance. However, there are usually more than one tower in certain given area so that the system can handle the increasing telephone traffic.
Tsunami
The
term of “tsunami” comes from the Japanese which means harbour ("tsu")
and wave ("nami"). A tsunami is a series of waves generated when water
in a lake or a sea is rapidly displaced on a massive scale.A tsunami can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. Such large vertical movements of the earth's crust can occur at plate boundaries.
Subduction of earthquakes are particularly effective in generating tsunami, and occur where denser oceanic plates slip under continental plates.
As the displaced water mass moves under the influence of gravity to regain its equilibrium, it radiates across the ocean like ripples on a pond.
Tsunami always bring great damage. Most of the damage is caused by the huge mass of water behind the initial wave front, as the height of the sea keeps rising fast and floods powerfully into the coastal area.
How do seasons happen?
Seasons come to us regularly. We have
probably noticed that it gets warmer in summer or dry season while it
get colder in the winter or wet season. However do we know how these
seasons change?
Seasons happen and change every
year. This happens because the earth tilts back and forth as it goes
around the sun. During the summer, the earth tilts toward the sun. It
makes half of the earth hotter. this condition is what we call summer.
During the other half of the year, the earth tilts away from the sun. As
a result, it makes that half of the earth cooler. This cool condition
is then what we call winter.
The different parts of the world
have the same season at different times. In the northern half of the
world , winter happens during the months of December, January and
February. The regions are such North America and Europe. In the other
hand, the southern half of the world have winter during the months of
June, July and August.The regions are like South America and Australia.
How does this difference happen? The same season happens at different
times because the top and bottom halves of the earth tilt away from the
sun at different times.
Photosynthesis
What is photosynthesis?
Photosynthesis is a food-making process that occurs in green plants. It
is the chief function of leaves. The word photosynthesis means putting
together with light. Green plants use energy from light to combine
carbon dioxide and water to make sugar and other chemical compounds.
How is the light used in photosynthesis?
The light used in photosynthesis
is absorbed by a green pigment called chlorophyll. Each food-making
cell in a plant leaf contains chlorophyll in small bodies called
chloroplasts. In chloroplast, light energy causes water drawn form the
soil to split into hydrogen and oxygen.
What are the steps of
photosynthesis process? Let me tell you the process of photosynthesis,
in a series of complicated steps, the hydrogen combines with carbon
dioxide from the air, forming a simple sugar. Oxygen from the water
molecules is given off in the process. From sugar together with
nitrogen, sulphur, and phosporus from the soil-green plants can make
starch, fat, protein, vitamins, and other complex compounds essential
for life. Photosynthesis provides the chemical energy that is needed to
produced these compounds.
How does Rain Happen?
Rain is the primary source of fresh
water for most areas of the world, providing suitable conditions for
diverse ecosystems, as well as water for hydroelectric power plants and
crop irrigation.
The phenomenon of rain is
actually a water circle. The concept of the water cycle involves the sun
heating the Earth's surface water and causing the surface water to
evaporate. The water vapor rises into the Earth's atmosphere. The water
in the atmosphere cools and condenses into liquid droplets. The droplets
grow until they are heavy and fall to the earth as precipitation which
can be in the form of rain or snow.
However, not all rain reaches
the surface. Some evaporates while falling through dry air. This is
called virga, a phenomenon which is often seen in hot, dry desert
regions.