what's the meaning of atmosphere?

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, people who travel above an altitude of 80.5 km (50 statute miles) are designated astronauts. An altitude of 120 km (~75 miles or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Kármán line, at 100 km (62 miles or 328,000 ft), is also frequently regarded as the boundary between atmosphere and outer space.

我有本Science書，係講述environment既。

書裡講述，Atmosphere係指大氣層的意思。
用途：Atmosphere protects the Earth from direct ultraviolet radiation from the Sun.
大氣層會保護地球，以免太陽的紫外線直接輻射地球。

1. 大氣[the S]
2. (某特定場所的)空氣[S]
The atmosphere of the city is very much polluted.
那個城市的空氣受到嚴重污染。
3. 氣氛[S1]
The talk was conducted in a cordial atmosphere.
會談是在熱情友好的氣氛中進行的。
4. 情趣;魅力[U]
The ancient palace has a lot of atmosphere.
這座古老的宮殿很有魅力。
5. (標準)氣壓[C]