Earth: The Living Planet PDF

 Earth is considered as a home of simple single-celled organisms up to the most complex life forms including humans. It is undeniable that the planet we live in is a rare planet as it is the only planet in our solar system that permits life. The different characteristics of Earth are responsib...

 Earth is considered as a home of simple single-celled organisms up to the most complex life forms including humans. It is undeniable that the planet we live in is a rare planet as it is the only planet in our solar system that permits life. The different characteristics of Earth are responsible for the proliferation of life.  The atmosphere consists of 78.1% nitrogen, 20.9% oxygen, 0.9% argon, 350 ppm carbon dioxide, and other components. The table below shows the major components in the atmosphere and their relative concentrations.  The presence of oxygen and carbon dioxide permits life on Earth. Carbon dioxide is used by photosynthetic organisms, such as plants and algae, to convert the energy from the sun to usable energy. The oxygen makes it livable for living organisms including humans for respiration and for our cells to function.  Earth’s atmosphere also protects us from the sun’s radiation. Thirty percent of the radiation is reflected away by the atmosphere, clouds, and the earth's surface. Another 25% is absorbed by the atmosphere and clouds, and the remaining 45% is absorbed by the earth’s surface.  The soil is a mixture of minerals, water, air, organic matter, and organisms. It is a living medium—a medium for growth of all kinds of vegetation. The soil promotes growth for plants by providing nutrients, water, and as a substrate for anchorage of roots.  In return, vegetation produces trees and forests cover, ensures the water and nutrient cycle, and prevents soil and wind erosion. This mutual relationship of the soil and vegetation makes our planet livable.  The hydrosphere contains all the water on our planet including ice and vapor. Nearly three- quarters of the earth’s surface is the sea and the ocean. The ocean houses many species of marine life and diverse mineral resources. Other forms of water include river, streams, and lakes.  Other than being a water reservoir, these forms of water are all sources of fish and shellfish that we consume. They also serve as thermostat and heat reservoir, especially the ocean. They also serve as ways for transportation.  The heat that drives the different systems necessary to support life on Earth come from two sources: a. Internal Heating of Earth b. External Heating from the Sun  Internal Heating of Earth – radiogenic heat from radioactive decay of materials in the core and mantle, and extruded via active tectonic activities. External Heating from the Sun – form of radiation which enters Earth. As sunlight strikes Earth, some of the heat is trapped by a layer of gases.  In the ocean, dark blue to violet represents warmer areas where there is little life due to lack of nutrients, and greens and reds represent cooler nutrient-rich areas. The nutrient-rich areas include coastal regions where cold water rises from the sea floor bringing nutrients along and areas at the mouths of rivers where the rivers have brought nutrients into the ocean from the land.  On land, green represents areas of abundant plant life, such as forests and grasslands, while tan and white represent areas where plant life is sparse or non-existent, such as the deserts in Africa and the Middle East and snow-cover and ice at the poles.  On land, green represents areas of abundant plant life, such as forests and grasslands, while tan and white represent areas where plant life is sparse or non-existent, such as the deserts in Africa and the Middle East and snow-cover and ice at the poles.  “We lose those battles as often as we succeed. The key, though, win or lose, is to never fail. And the only way to fail is not to fight. So fight until you can't fight anymore. Never let go. Never give up. Never run. Never surrender. Fight the good fight, you fight even when it seems inevitable you're about to go down swinging.” -Dr. Amelia Shepherd