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The Earth's Atmosphere
The Earth's Atmosphere
The Earth's Atmosphere
The earth is surrounded by a layer of gases called the atmosphere. The atmosphere is very important to life on Earth and does many things to help protect life and help life to survive.
It is a mixture of gases that surrounds the Earth. It helps make life possible by providing us with air to breathe, shielding us from harmful ultraviolet (UV) radiation coming from the Sun, trapping heat to warm the planet, and preventing extreme temperature differences between day and night.
The atmosphere protects Earth like a big blanket of insulation. It absorbs the heat from the Sun and keeps the heat inside the atmosphere helping the Earth to stay warm, called the Greenhouse Effect. It also keeps the overall temperature of the Earth fairly steady, especially between night and day. So we don't get too cold at night and too hot during the day. There is also a portion of the atmosphere called the ozone layer. The ozone layer helps to protect the earth from the Sun's radiation.
This big blanket also helps to form our weather patterns and climate. The weather keeps too much hot air from forming in one place and causes storms and rainfall. All of these things are important to life and the Earth's ecology.
The atmosphere allows sunlight to penetrate the Earth's surface while also retaining some of the sun's heat. This helps maintain the planet's temperature, keeping it warm, even during the night and in the winter.
The atmosphere is the air that plants and animals breathe to survive. The atmosphere is made up of mostly nitrogen (78%) and oxygen (21%). There are lots of other gases that are part of the atmosphere, but in much smaller amounts. These include argon, carbon dioxide, neon, helium, hydrogen, and more. Oxygen is needed by animals to breathe and carbon dioxide is used by plant in photosynthesis.
Temperature of the Earth
On Earth, the temperature is kept at a comfortable level since the atmosphere traps some of the radiant heat from the Sun, warming the surface and sustaining life. This trapping is done by greenhouse gases in our atmosphere, which absorbs some infrared heat radiation and re-radiates some to the surface of the Earth, warming it.[2] This process, as explained above, is the natural greenhouse effect and is completely necessary to our life on this planet. NASA has reported that the average temperature of the Earth as a result of the warming from the greenhouse effect is 15°C.[7] This average temperature increase is starting to harm various environments.
Temperature of the Earth without Greenhouse Effect
Without the influence of the greenhouse effect on our planet, the average surface temperature would be 255 Kelvin - which can also be expressed as -18°C or 0°F.[8] If this were the case, water on Earth would freeze and life as we know it would not exist. The average temperature of the Earth is actually approximately 15°C, a significant difference![9]
Layer 1
Sea Level To 20 Km
Layer 2
20 Km To 50 Km
Layer 3
50 Km To 85 Km
Layer 4
85 Km To 690 Km
Layer 5
690 Km To 10,000 Km
Troposphere - The troposphere is the layer next to the ground or surface of the Earth. It covers around 6-20 Km high. This is where we live and even where planes fly. Around 80% of the mass of the atmosphere is in the troposphere. The troposphere is heated by the surface of the Earth.
Stratosphere - The stratosphere extends for the next 50 Km after the troposphere. Unlike the troposphere the stratosphere gets its heat by the Ozone Layer absorbing radiation from the sun. As a result, it gets warmer the further away you get from the Earth. Weather balloons go as high as the stratosphere.
Mesosphere - The mesosphere covers the next 85 Km beyond the stratosphere. This is where most meteors burn up upon entry. The coldest place on Earth is at the top of the mesosphere.
Thermosphere - The thermosphere is next and the air is very thin here. Temperatures can get extremely hot in the thermosphere.
Exosphere - The last layer goes all the way to 10,000 km above the Earth's surface.
Air is a mixture of gases which makes up the Earth’s atmosphere. These gases are colorless and odorless and hence, we can’t see them but only feel them. The atmosphere is an ocean of these gases. It consists of 78% nitrogen, 21% oxygen and 1 % other gases and water vapour. The composition of air does not change as you travel through the layers of the atmosphere. What changes is the number of molecules. The air molecules decrease and become less. The moisture content varies from place to place. Arid regions have less moisture content as compared to wetlands.
Other Components of Air
Sulfur dioxide(SO2) – 1.0 ppm
Methane(CH4 )-2.0 ppm
Nitrous oxide(N2O) – 0.5 ppm
Ozone(O3)-0 to 0.07 ppm
Nitrogen dioxide(NO2) – 0.02 ppm
Iodine(I2)-0.01 ppm
Carbon monoxide(CO) – 0 to trace ppm
Ammonia(NH3)-0 to trace ppm
Properties of Air
Colourless and Odourless:
Air generally has no colour or odour. It is an invisible matter that can only be felt. All living things breathe air for their survival. Moving air is called wind.
Occupy Space:
It is a mixture of different gases. Hence, like every other matter, they also occupy space. On blowing, a balloon expands because the air being blown into it fills up the empty space.
Air Exerts Pressure:
It has weight, and the pressure exerted by the weight of air is known as air pressure. Due to gravity, this mixture of gases near the surface is denser than at high altitudes. This is why the gaseous atmosphere in the mountains is thinner than that at the surface.
Expansion:
Another property is its expanding property. On heating, it expands and occupies more space. The more it expands, the thinner it becomes. Hence, the pressure of the warm wind is lower than that of cold wind.
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