The Nature of Planetary Atmospheres

By Arpit and Hamzah Ismail

Introduction: Exploring the Cosmic Air

Other planetary atmospheres can provide the planetary scientist with useful information concerning environmental conditions and processes occurring on very different planets. Whether it is the thick, foul clouds covering Venus or the thin, cold fog enveloping Pluto, an understanding of the atmosphere of those planets helps us learn about the possibility of life there, how their climates work, and how they evolved over time.

Earth's Atmosphere: A Breath of Life

Nitrogen makes up 78% of the Earth's atmosphere; oxygen, 21%; and trace gases. This mixture is what makes life possible. It is divided into different layers based on the temperature gradients:

Troposphere: In this layer, weather phenomena extend up to a height of approximately 8-15 km above Earth's surface. With increasing altitude, air temperature decreases.

Stratosphere: Location of the ozone layer, which absorbs and scatters most of the ultraviolet solar radiation; this layer begins right after the previous one and goes to about 50 km from the Earth's surface.

Mesosphere: This atmospheric layer again shows a decrease in temperatures, amounting to the lowest temperatures recorded in the atmosphere of Earth. It ranges around 50 km to 85 km above Earth's surface.

Thermosphere: The increases in temperature are most dramatic in the height between 85 km to 600 km in the ionosphere, the region containing the aurora

Exosphere: Outermost layer, where few are the number of particles of the atmosphere that can escape into space. The exosphere begins approximately 600 km above the surface.

This photo by Unknown Author is licensed under CC BY-SA

Venusian Atmosphere:

An Inhospitable Thick Blanket Venus's atmosphere consists mainly of carbon dioxide, accounting for 96.5%, with sulphuric acid clouds, which makes it exceedingly dense and heavy. The atmosphere has caused a runaway greenhouse effect, trapping in heat which causes surface temperatures up to 467°C (872°F), even hotter than Mercury, yet Venus orbits farther from the Sun. The atmospheric pressure at the surface is roughly 92 times that of the Earth's surface, and because of dense cloud cover, no features on the surface are visible from orbit.

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Atmosphere of Mars: Sparse and Cold

Mars has a super-thin atmosphere of 95% carbon dioxide and, with traces of nitrogen and argon, its surface atmospheric pressure is less than 1% of Earth's. Because it has such little air pressure at the surface, huge temperature variations exist between day and night. It gets hit by dust storms frequently, sometimes blanketing all areas of the planet. Due to its thinness, its average temperature is -60°C (80°F).

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Jupiter's Atmosphere: A Gaseous Giant

A Gaseous Giant The atmosphere, generally, is composed of 90% hydrogen and 10% helium. Besides, traces of other gases like methane, ammonia, etc., are present. The most distinctive in the atmosphere is the strong banded cloud formations and the Great Red Spot. The atmosphere can be divided into three different layers: troposphere, stratosphere, and thermosphere. Owing to the absence of solid ground, these layers just grade into each other.

High temperatures and pressures at the core account for the complex atmospheric dynamics and deep, colorful cloud formations.

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Saturn's Atmosphere: Ringed and Dynamic

Saturn's atmosphere is composed, like Jupiter's, of primarily hydrogen and helium with traces of methane, ammonia, and water vapor. It has really prominent banded structures and the planet's typical rings, which are made up of chunks of ice and rock. The atmosphere of Saturn also hosts extreme temperature variations and powerful winds, especially within its outer layers. This unique atmospheric phenomenon may be attributed to the lower gravitation and rapid rotation of the planet.

Uranus and Neptune: The Ice Giants

Uranus and Neptune have atmospheres containing hydrogen, helium, and other "ices" of water, ammonia, and methane. The atmospheric compositions of both are only partially understood because they lie so far from Earth. The atmosphere of Uranus is quite boring and presents with a faint blue color because methane should absorb most of the red light. Neptune exhibits a bit more active meteorology compared to Uranus and rather vibrant deep blue color caused by methane. These celestial bodies have atmospheric strata that resemble the gas giants', but with greater concentration of icy compounds.

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Glossary:

• Stratosphere: This is the layer beyond troposphere. It includes the ozone layer which experiences the absorption of ultraviolet radiation.

• Mesosphere: Temperature keeps dropping as one moves above the stratosphere and reaches some of the lowest temperatures in the atmosphere.

• Thermosphere: The layer where increased altitude means increased temperature, and the location of the auroras.

• Exosphere: The outermost layer of the atmosphere where the particles get escaped into space.

• Greenhouse Effect: The warming of a planet's surface caused by the trapping of heat by its atmosphere.

• Runaway Greenhouse Effect: The ultimate form of the greenhouse effect results in super-high surface temperatures.

• Gaseous Giant: A Planet of predominantly gaseous material, as in the cases of Jupiter and Saturn.

• Ice Giant: A subclass of planets with a significant portion of icy material in its atmospheric composition; Uranus and Neptune belong to this class.

• Aurora: A natural light in the sky usually in the polar regions that results when the charged particles of the earth enter the atmosphere.

  
  

  Grasping the dynamics of planetary atmospheres enhances our comprehension of the solar system while simultaneously offering a framework for comparative analysis within climate and atmospheric science. The atmosphere of each planet serves as a source of insights regarding its historical development, chemical makeup, and viability for sustaining life.