Essay on Earth
Only one astronomical object, Earth, is known to support life, and it is the third planet from the Sun. Even though there is a lot of water in the Solar System, only Earth has liquid surface water. Earth's arctic ice, lakes, and rivers are dwarfed by the ocean, which makes up around 71 percent of the planet's surface. Continents and islands make up the remaining 29% of the Earth's surface. Mountains, volcanoes, and earthquakes are the results of the interaction between the tectonic plates that make up the Earth's surface.
The magnetic field produced by the planet's liquid outer core directs destructive solar winds away from Earth. The majority of the Earth's atmosphere is composed of nitrogen and oxygen. As a result of air and ocean circulation, solar energy is distributed more evenly in tropical regions than it is in polar ones. The atmosphere contains large amounts of water vapour, which creates the majority of the planet's clouds. Carbon dioxide (CO2) and other greenhouse gases trap solar energy near the earth's surface. Along with elevation and proximity to oceans that act as climate regulators, latitude determines a region's climate. The majority of regions often suffer extreme weather, which has a big effect on daily living. Examples include tropical cyclones, thunderstorms, and heat waves.
Formation of Earth
Over 4.5 billion years ago, Earth was formed. Life first flourished in the ocean after it had been established during the first billion years of Earth's existence. Two billion years ago, Earth's Great Oxidation Event took place as a result of the wide spread of life and its subsequent effects on the planet's surface and atmosphere. Since their appearance 300,000 years ago, humans have grown to a global population of about 8 billion. Humans are reliant on the biosphere and natural resources of the planet to survive, but they are having a growing negative impact on the ecosystem. The climate, soils, oceans, and ecosystems of the Earth are in an unsustainable state right now, jeopardising human life and perhaps hastening the extinction of other living forms.
Earth's Physical Properties
Earth has a roughly spherical form. The equator bulges and the poles slightly flatten as a result of the rotation of the Earth. Since the equatorial diameter of the Earth is 43 kilometres (27 mi) bigger than the pole-to-pole diameter, an oblate spheroid is a better fit for the planet's shape.
The reference spheroid has a 12,742 km average diameter (7,918 mi). While Mount Everest, which is 8,848 metres (29,029 feet) above local sea level, has a 0.14 percent deviation. The top of Ecuador's tropical Chimborazo volcano is the farthest point from the planet's centre of mass (6,384.4 km or 3,967.1 mi).
Similar to the other terrestrial planets, the interior of Earth is separated into strata based on its chemical or physical (rheological) characteristics. A chemically unique silicate solid crust serves as the outermost layer, while a highly viscous solid mantle serves as the layer beneath it. The crust is around 6 kilometres (3.7 mi) thick under the oceans and 30 to 50 kilometres (19 to 31 miles) deep on the continents. The lithosphere, which is separated into independently moving tectonic plates, is made up of the crust and the cold, stiff top of the upper mantle.
The asthenosphere, a layer with relatively low viscosity, lies below the lithosphere and supports it. Between the upper and deep mantle, there are considerable changes in the crystal structure at depths of 410 and 660 km (250 and 410 mi), respectively. A very low viscosity liquid outer core is positioned below the mantle, above a solid inner core. A solid inner core is positioned above an incredibly low viscosity liquid outer core beneath the mantle. Although both slightly higher and significantly lower rates have also been proposed, it has been suggested that Earth's inner core rotates with an angular velocity that is somewhat higher than that of the planet as a whole, advancing by 0.1-0.5° per year. The inner core's radius is roughly one-fifth that of the Earth.
Field of Gravitation
The acceleration that objects experience owing to Earth's mass distribution is known as gravity. The gravitational acceleration is about 9.8 m/s2 (32 ft/s2) close to the surface of the Earth. Gravitational anomalies, sometimes referred to as local and regional changes in the Earth's gravitational field, are caused by local variations in topography, geology, and underlying tectonic structure.
The main source of the magnetic field is the Earth's core, where a dynamo mechanism transforms the kinetic energy of chemically driven convection into the energy of the electrical and magnetic fields. The field emanates from the core, travels through the mantle, and then rises to the surface of the Earth, where it roughly assumes the shape of a dipole. The geographic poles of Earth are not far from the dipole's poles. At the magnetic field's equator, the magnetic field's surface intensity is 3.05 10-5 T, and its magnetic dipole moment, which was 7.79 1022 Am2 in the year 2000 but is currently declining by over 6 percent every century, is 7.79 1022 Am2. Magnetic poles drift and sporadically reposition due to the turbulent convection processes in the core. This causes the primary field to fluctuate over time and experience field reversals that typically happen a few times every million years. The most recent reversal occurred around 700000 years ago.
The percentages of nitrogen, oxygen and other gases in the atmosphere of Earth are roughly 78%, 21%, and 1%, respectively. These gases are found in the layers known as the troposphere, stratosphere, thermosphere, and exosphere. Each layer is distinguished by specific characteristics like temperature and pressure.
The population of the Earth topped seven billion early in the 2010s. By the end of the 21st century, it is expected to reach a peak of about ten billion. Sub-Saharan Africa is predicted to experience the majority of the growth. Asia has the highest concentration of people in the world, yet population density varies widely around the globe. By 2050, 68 percent of the world's population is expected to live in cities as opposed to rural areas. The Northern Hemisphere has 68 percent of the world's landmass. 90% of people reside in the Northern Hemisphere, in part due to the preponderance of land mass.
Potassium-40, uranium-238, and thorium-232 are the principal heat-producing isotopes inside the Earth. There could be a pressure of 360 GPa and temperatures of up to 6,000 °C at the centre. Since a considerable percentage of heat is created by radioactive decay, scientists hypothesise that earlier in Earth's history, before isotopes with brief half-lives were depleted, its heat production was much greater. At that time double the heat of today would have been produced causing speeding up plate tectonics and mantle convection while enabling the formation of unusual igneous rocks such as komatiites, which are hardly formed today.
The Earth's ecosystem
The ecosystems of a planet are home to the living things that make up the biosphere. The biosphere is separated into various biomes, each of which is home to a group of largely comparable plants and animals. On land, variations in latitude, altitude above sea level, and humidity are the main factors that distinguish biomes. Species diversity is highest in damp lowlands at equatorial latitudes; it is rather sparse in terrestrial biomes found in the Arctic or Antarctic Circles, at high elevations, or in extremely arid regions. The number of species now living on Earth varies widely; the vast majority of species are unidentified. Over 99 percent of all species that have ever lived on Earth are no longer existing.
Even if life did not first exist on the planet, a planet that can support it is referred to as habitable. The distance of the Earth from the Sun, the eccentricity of its orbit, its rate of rotation, its geological past, its supporting atmosphere, and its magnetic field all have an impact on the climate at the surface today. Earth offers liquid water, an environment that allows for the assembly and interaction of complex organic compounds, and enough energy to support metabolism. Nutrients can be absorbed by plants from the air, soil, and water. The various species regularly exchange these nutrients.
"Natural catastrophe or disaster" is defined as "the detrimental effect following an actual occurrence of a natural hazard in the event that it significantly harms a community."
A natural disaster typically causes economic devastation in addition to the possibility of human or property loss. The resilience of the populace and the state of the infrastructure will determine how much damage is done. The following are a few examples of natural hazards: avalanches, coastal floods, cold waves, droughts, earthquakes, heat waves, hurricanes (tropical cyclones), landslides, lightning, riverine flooding, high winds, tornadoes, tsunamis, volcanic activity, wildfires, and winter weather.
Tropical cyclones, which include hurricanes and typhoons, occur throughout the majority of the Earth's surface and have a significant impact on local life. These incidents caused an average of 11,800 human fatalities annually from 1980 to 2000. There are many locations that are vulnerable to calamities and disasters like earthquakes, landslides, tsunamis, volcanic eruptions, blizzards, floods, droughts, and wildfires. Because of air and water pollution, acid rain, loss of flora (due to overgrazing, deforestation, and desertification), loss of wildlife, species extinction, soil degradation, soil depletion, and erosion can be seen in many different places. Global warming is brought on by greenhouse gases that people release into the atmosphere.