Earth Sciences

How is the weather forecast made?

Weather is dependent on a number of factors like humidity, atmospheric pressure, ambient temperatures, rains, wind speed and direction and more. Different instruments are used to measure each of these parameters. The meteorological department of each country collects this information to forecast the weather.

Anemometer
Anemometer is used to measure the direction of the wind, hygrometer is used to measure the humidity in the air, rainfall is measured by the rain gauge, and the sunshine recorder measures the duration of the sunshine. Since various factors collectively determine the weather, each of it is separately measured and then combined at the meteorological office to forecast the weather of a particular place. Barometers are used to get the measure of the atmospheric pressure. The atmospheric pressure and the direction and speed of the wind are calculated to determine storms and hurricanes. Satellites are also being used to determine weather with more accuracy.

Nowcasting
Nowcasting is referred to as the weather forecasting in the immediate next six hours. In the small time range, it is easier to forecast smaller features of the weather such as showers and thunderstorms with more accuracy. Weather forecast for immediate period is more accurate than for larger time gaps.

In recent times, human input to forecast weather is restricted only to selecting a model to fore cast weather. The rest of it is done by instruments and computers. The data is fed to the computer of the various weather parameters and the weather is forecast is generated by the machine. Humans use the model results and interpret them into weather forecasts for the common man to understand. Humans are also helpful to forecast weather with small inputs which are not useful for machines. With small inputs professionals can forecast the weather.

The simplest method to forecast weather is persistence. This method basically relies on today’s weather to forecast tomorrow’s weather. This method is quite accurate when the weather conditions are stable. It is useful for both short and long range forecasts.

How were the Himalayas created?

The real beauty of the country India lies in its flora and fauna, its flowing rivers and yes, how can we not mention, the mighty Himalayas. The Himalayas are one of the most beautiful mountain ranges of the world. Often do we wonder what had been the story behinds their evolution. It must surely have taken epochs for these mighty mountains to form.

The story behind their evolution goes like this. India was way back believed to be a part of what was called the Gondwanaland. Between the Eurasian continent and the Gondwanaland, existed, what was called the Tethyan Ocean. This ocean separated both these pieces of land from each other. About a billion years ago, the Aravali Ranges that are now located in the state of Rajasthan in India was first a group of large mountain ranges, higher than the today’s Himalayas. They stretched over a huge area.

A collision took place about 140 million years ago and India started to move towards the North. The two continents were joined at a point called the Indus-Yarlung Suture Zone. This is the point where these two mighty rivers of the Himalayas flow today. Along the side of this Indus-Yarlung Suture zone, about 60 million years ago, the Indian and the Asian plates came in close proximity with each other. This marked the slowing down of the Indian continent’s northward movement. It became as slow as about three centimeters per year.

When this collision had taken place the Tethyan Ocean contracted. The rocks that were situated in this area along with the mountains in the northern part of India and the sand and rock deposits joined together. This marked the creation of the beautiful Himalayas.

The Himalayas did not form its huge structure stretching over a vast area at once. At the very beginning were formed the Trans Himalayas. The southern part of this portion has the highest peaks of the whole mountain range. Crystalline rock is also located here. They are about two billion years old, the oldest of all the rocks found in the Himalayan range. They are in the bottommost layers called the Central Thrust.

After this, Shivalik range was formed. They were a result of the continuous erosions of the Aravalis. Shivaliks are the lower range of Himalayas. The history of Shivaliks is proven by the old fossils found at that place and hence the age of Himalayas has been estimated.

The next phase marked the formation of Garhwal, Nanda Devi and other on the central axis. At this time itself the Bhagirathi were formed. They are mountain ranges made up of leucogranites, white in color.

The last upheaval happened in the Trans Himalayas and the Karakorum and in the region of Tibet. This region has the highest land mass on this planet. It stretches over an area of 2.5 billion square kilometers. It is still continuously rising. In the past one million years it’s gone up about 5000 meters high. In every ten years it rises about 10 meters high.

After the whole formation began the ice age during which Pangong and the Chandratal glaciers were formed. Many Himalayan lakes and rivers came in to existence during that time.

The major rivers of the Himalayan range flow in the pious region of Kailasha. In the north flows the Indus, in the east, the Yarlung Brahmaputra, the west has Sutlej flowing and Ganga and Karnali in south and the southwest region. The Kailasha range is about 30 million years old.

The eastern Himalayas less wide and deep than the Western Himalayas have a stark difference in the climatic conditions. Here the climate is not harsh unlike other portions of Himalayas and heavy rainfall often takes place.

The story behind the Himalayas continue to fascinate geologists and their constant upheaval is astonishing and worth admiring.

How is soil formed?

The uppermost layer of earth’s crust is known as soil. Weathering of rocks, metamorphosis, and chemical processes leads to formation of soil. Thus soil can be called rock in its final state of decay. Soil formation is a very slow process which can even take thousands of years. Soil which is found lying in the original place of its formation is called sedentary soil; whereas, the ones that are carried from other sites by various natural agents are called transported soil.

Early stages of formation
Molten magma that accumulated on the earth’s surface cooled and formed igneous rocks. Then erosion and weathering of rocks began. Due to weathering rocks broke down into small pieces and mingled with organic matters. Over time a thin layer of soil got formed. When the herbivorous animals die and their bodies decay, the decayed matters add to the thickness of soil and enrich it. This process goes on till soil formation becomes complete.

Soil layers
Soil formation begins at the topmost layer of surface of earth but it works differently in the layers beneath. The uppermost surface which gets maximum exposure to changes differs radically from the layers of soil, also called horizons, which lie below this bed. These horizons vary in terms of color texture and structure. The horizons from top to bottom are named as O horizon, A horizon, E horizon, B horizon and C Horizon respectively.

Factors helping soil formation

• Weathered bedrock and natural agents that carry out transportation of soil.

• Climate helps in soil formation. Temperature and moisture content directly affect weathering and leaching. The quantity and type of precipitation has a direct influence on soil formation.

• Biological factors such as plants, fungi, bacteria, animals and human beings too affect soil formation, directly and indirectly.

• Last, but not the least, time contributes in the development as well as formation of soil.

How is snow formed?

Snow is a form of precipitation that occurs in the form of crystalline water ice. It consists of multitude of snowflakes that fall from clouds. The precipitation of crystalline water ice leads to the formation of snow. Snow is considered as a granular material since it contains tiny particles. Snowflakes come in a variety of sizes and shapes. Types which fall in the form of a ball due to melting and refreezing, rather than a flake, are known as graupel, with ice pellets and snow grains as examples of graupel.

Early stages of snow formation
Snow in its familiar tangible form reaches such state though a formation process that starts in the earth’s atmosphere. Temperature and levels of moisture contribute significantly to the snow formation. When a tiny crystal comes in contact with a huge amount of moisture in the air, condensation begins. Thus the ice crystals obtain various shapes and sizes. The tiny condensed drops cling to each other and get transformed into ice crystals when exposed to extremely low temperature, less than 32 degrees Fahrenheit.

Next stage of formation
The droplets then begin to freeze randomly by sticking to each other and lead to the formation of heavy drops which unable to suspend in the atmosphere, tend to fall towards the ground surface. These crystals pass through varying degrees of temperature and precipitate as snow. Interestingly enough, the ‘ice crystals’ which fall from the sky is known as snow.

Final shape of snow
Snowflakes come in different shapes and sizes. Traditionally every snow flake has six sides, each flake is unique. While traveling towards the ground, the snowflakes might permeate surface air, either warmer or cooler. Thus the flakes go through melting and refreezing. Various shapes and sizes are formed due to this rigorous process of melting and freezing till the flakes finally hit the ground. On reaching the ground, the snowflakes again melt and bond with other flakes. All the intricacy in the patterns of these flakes is lost. Provided, the surface temperature is extremely low, the snow would eventually form a hard coated crest. Warm temperature would make the snow melt and become mushy eventually lose structure and form water.

What are ocean trenches?

Ocean trenches are depressions that are created on the ocean floor. These ocean trenches are normally very narrow, but they can be really deep. Some of the ocean trenches are really deep, and it would take a lot of time for the humans to explore such sites inside the ocean floor. Hence, you will require a lot of technical assistance and a team of experts that would ensure that you are safe and any kind of risk is minimized.

The Earth’s lithosphere is generally made up of different slabs that are better known as plates and these ocean trenches normally occur where two plates meet and there is a thin divide in between. Hence, those who are interested in diving deeper to explore ocean trenches should also have a thorough knowledge about tectonic plates as the information can help them to learn more interesting facts about ocean trenches.

These trenches are common if there is a lot of tectonic activity happening and such areas are called subduction zones.

One easy way to spot ocean trenches below the sea is to locate volcanic islands. Most of the ocean trenches are very close to the volcanic islands, and this happens because one tectonic plate moves upwards then the other moves downwards creating an ocean trench.

Currently, Mariana Trench’s Challenger Deep is considered to be the deepest ocean trench in the world as its depth is more than the height of Mount Everest. However, few explorations have provided substantial information that aquatic life still exists in such deeper places even though there is no sunlight, and the water pressure is immense.