The word troposphere originates from the Greek word tropos, meaning change; troposphere means circle of change. In the early 1900s, Philippe Teisserenc de Bort studied the lower atmosphere and was the first to discover the temperature gradients between the troposphere and stratosphere using weather balloons. He named the Earth’s closest layer as troposphere as well as the upper limit of this layer, the tropopause. The layers of the planet’s atmosphere, from the outermost layer to its surface, are the exosphere, thermosphere, mesosphere, stratosphere, and troposphere.
In the below article Pritish Halder gives a brief about the closest layer of earth called Troposphere
What is the Troposphere?
The Earth is covered in a blanket of gases creating the atmosphere, which is composed of five layers. The layer closest to the Earth’s surface is the troposphere. This layer extends up to twenty kilometers above the Earth. The troposphere is essential as it contains the Earth’s weather as well as greenhouse gases to maintain the temperature on Earth.
What is the tropopause?
The tropopause is the gradient layer between the troposphere and the stratosphere. The height of the tropopause varies considerably with prevailing jet streams, fronts, and seasons, although the temperature remains somewhat constant compared to the troposphere, which decreases in temperature at a constant rate. This is particularly important for pilots as it affects turbulence in a given area.
What does the troposphere do, and why is it important? Each of the Earth’s atmospheric layers protects the Earth. For example, the mesosphere burns up many incoming meteors. The stratosphere contains the ozone layer, which helps absorb dangerous ultraviolet rays. However, the troposphere is especially significant, as highlighted below:
- Has the greatest density of all the atmospheric layers (1.225 km/m3 at sea level @ 59 degrees F).
- Mass is 75% of the total atmosphere of Earth.
- Height is approximately 7- 20 km, most significant at the equator, least at the poles.
- Temperature decreases with altitude – averages are 62 degrees F at sea level to -60 degrees F at the tropopause.
- Air pressure is 1013 mb on average at sea level and decreases with altitude.
- Contains 99% of Earth’s water vapor.
- Gas components: 78% Nitrogen, 21% Oxygen, 0.9% argon, and trace amounts of carbon dioxide, methane, ozone, hydrogen, and other compounds. Water vapor ranges from 0 – 4%.
- Contains Earth’s weather, although some cumulonimbus clouds reach into the stratosphere.
- Water condenses and precipitates in the upper troposphere, which explains why weather events do not occur in the stratosphere.
- Global winds and fronts occur in the troposphere creating weather events such as thunderstorms, hurricanes, tornadoes, and blizzards.
- Photosynthesis and the water cycle are contained in this layer, although some cirrus clouds reach the stratosphere.
The gas composition of the troposphere is mainly nitrogen and oxygen, with a small percentage of argon and other trace elements. Water vapor content is variable depending upon air temperature as warmer air holds a higher water vapor content. Percentages of the atmospheric gases are listed below:
- Nitrogen 78%
- Oxygen 21%
- Argon 0.9%
- Trace elements 0.1%
Trace elements in the atmosphere include carbon dioxide, water vapor, ozone, nitrous oxide, methane, halocarbons, neon, and hydrogen. While argon and neon are inert elements, the other gases in the atmosphere are significant and described below:
- Nitrogen – Essential for building amino acids for protein synthesis in organisms
- Oxygen – Essential for cellular respiration in organisms
- Carbon dioxide – While essential for the process of photosynthesis in plants, this gas is a potent greenhouse gas that helps keep the Earth warm. Higher concentrations may be associated with climate change due to higher global temperatures.
- Water vapor – Essential for the water cycle, water vapor is also a greenhouse gas that helps maintain global temperatures.
- Ozone – While concentrations are minimal, ozone is a greenhouse gas produced by pollution.
- Nitrous oxide – A relatively inert gas in the troposphere, it can reach the stratosphere. There, nitrous oxide reacts with oxygen ions to produce nitric oxide, which breaks down ozone, a critical layer that absorbs types of solar radiation.
- Methane – A greenhouse gas, this compound is released into the atmosphere primarily from natural processes on Earth.
- Halocarbons – These compounds, produced by human activities, is a potent greenhouse gas. It has been estimated to be up to 15 thousand times more potent than carbon dioxide in absorbing heat.