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The correct answer is Gravity. The Earth is surrounded by a layer of gases called the atmosphere, which is composed mainly of nitrogen, oxygen, carbon dioxide, and trace gases. These gases are held close to the planet due to the force of gravity, which attracts all matter towards the center of the Earth. Without gravity, the atmospheric air would drift off into space, making life on Earth impossible.
Gravity acts uniformly on all particles of air, creating air pressure at different altitudes. The pressure is highest near the Earth’s surface and decreases with height. This is why mountains have thinner air at higher altitudes — gravity pulls air molecules toward the lower regions, keeping most of the air dense close to the ground.
Other options, such as winds, clouds, or the Earth’s rotation, do not hold the atmosphere in place. Winds are movements of air caused by pressure differences, clouds are condensed water vapor, and the Earth’s rotation causes the Coriolis effect, which influences wind and ocean currents, but none of these prevent air from escaping. Gravity is the fundamental force keeping the atmosphere stable.
The presence of the atmosphere due to gravity also allows life to thrive. It protects organisms from harmful ultraviolet (UV) rays, regulates temperature, enables respiration, and allows water cycles to function properly. Scientists calculate the effect of gravity on the atmosphere using the barometric formula, which shows the relationship between pressure, altitude, and temperature.
Atmospheric air = mixture of gases (Nâ‚‚, Oâ‚‚, COâ‚‚, others).
Held to Earth by gravity, not winds, clouds, or rotation.
Gravity creates air pressure that decreases with height.
Essential for life, climate, and protection from harmful radiation.
Without gravity, the atmosphere would escape into space.
👉 Final Answer: The atmospheric air is held to the Earth by Gravity.
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