Search results
People also ask
What are the three main components of the atmosphere?
What is the composition of Earth's atmosphere?
What are the layers of Earth's atmosphere?
What is the Earth's atmosphere like?
What atoms are in the atmosphere?
What elements make up earth's air?
Nitrogen and oxygen are by far the most common gases in our atmosphere. Dry air is composed of about 78% nitrogen (N 2) and about 21% oxygen (O 2). The remaining less than 1% of the atmosphere is a mixture of gases, including argon (Ar) and carbon dioxide (CO 2).
- Overview
- Energy budget
atmosphere, the gas and aerosol envelope that extends from the ocean, land, and ice-covered surface of a planet outward into space. The density of the atmosphere decreases outward, because the gravitational attraction of the planet, which pulls the gases and aerosols (microscopic suspended particles of dust, soot, smoke, or chemicals) inward, is greatest close to the surface. Atmospheres of some planetary bodies, such as Mercury, are almost nonexistent, as the primordial atmosphere has escaped the relatively low gravitational attraction of the planet and has been released into space. Other planets, such as Venus, Earth, Mars, and the giant outer planets of the solar system, have retained an atmosphere. In addition, Earth’s atmosphere has been able to contain water in each of its three phases (solid, liquid, and gas), which has been essential for the development of life on the planet.
The evolution of Earth’s current atmosphere is not completely understood. It is thought that the current atmosphere resulted from a gradual release of gases both from the planet’s interior and from the metabolic activities of life-forms—as opposed to the primordial atmosphere, which developed by outgassing (venting) during the original formation of the planet. Current volcanic gaseous emissions include water vapour (H2O), carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen sulfide (H2S), carbon monoxide (CO), chlorine (Cl), fluorine (F), and diatomic nitrogen (N2; consisting of two atoms in a single molecule), as well as traces of other substances. Approximately 85 percent of volcanic emissions are in the form of water vapour. In contrast, carbon dioxide is about 10 percent of the effluent.
During the early evolution of the atmosphere on Earth, water must have been able to exist as a liquid, since the oceans have been present for at least three billion years. Given that solar output four billion years ago was only about 60 percent of what it is today, enhanced levels of carbon dioxide and perhaps ammonia (NH3) must have been present in order to retard the loss of infrared radiation into space. The initial life-forms that evolved in this environment must have been anaerobic (i.e., surviving in the absence of oxygen). In addition, they must have been able to resist the biologically destructive ultraviolet radiation in sunlight, which was not absorbed by a layer of ozone as it is now.
Once organisms developed the capability for photosynthesis, oxygen was produced in large quantities. The buildup of oxygen in the atmosphere also permitted the development of the ozone layer as O2 molecules were dissociated into monatomic oxygen (O; consisting of single oxygen atoms) and recombined with other O2 molecules to form triatomic ozone molecules (O3). The capability for photosynthesis arose in primitive forms of plants between two and three billion years ago. Previous to the evolution of photosynthetic organisms, oxygen was produced in limited quantities as a by-product of the decomposition of water vapour by ultraviolet radiation.
Britannica Quiz
27 True-or-False Questions from Britannica’s Most Difficult Science Quizzes
Earth’s atmosphere is bounded at the bottom by water and land—that is, by the surface of Earth. Heating of this surface is accomplished by three physical processes—radiation, conduction, and convection—and the temperature at the interface of the atmosphere and surface is a result of this heating.
The relative contributions of each process depend on the wind, temperature, and moisture structure in the atmosphere immediately above the surface, the intensity of solar insolation, and the physical characteristics of the surface. The temperature occurring at this interface is of critical importance in determining how suitable a location is for different forms of life.
- Roger A. Pielke
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.
An atmosphere is a blanket of gases that surrounds Earth. It is held near the surface of the planet by Earth’s gravitational attraction. Argon, oxygen and nitrogen from the three main constituents of the atmosphere.
- The process of gases in the Earth’s atmosphere trapping the Sun’s heat is known as the greenhouse effect. Due to this process, the Earth is much wa...
- The earth’s atmosphere doesn’t end at a specific place. The higher we go, the thinner the atmosphere gets. There is no clear distinction between th...
- The stratosphere contains the ozone layer. The stratospheric ozone layer absorbs most of the sun’s ultraviolet light and thereby protects the earth.
- A barometer is used to measure air pressure.
One of the main components of Earth’s interdependent physical systems is the atmosphere. An atmosphere is made of the layers of gases surrounding a planet or other celestial body. Earth’s atmosphere is composed of about 78% nitrogen, 21% oxygen, and one percent other gases.
Jun 25, 2024 · Earth’s atmosphere has a layered structure. From the ground toward the sky, the layers are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Another layer, called the ionosphere, extends from the mesosphere to the exosphere. Beyond the exosphere is outer space.
May 13, 2024 · There are five main layers that make up the atmosphere, differentiated by factors such as temperature, chemical composition, and air density. An illustration of the five different layers of Earth’s atmosphere. NASA GSFC/Mary Pat Hrybyk-Keith. 1. Troposphere. The troposphere is the lowermost atmospheric layer.
