Correct Option
The correct option is (a) 1 only.
Explanation
The atmosphere acts as a protective insulating layer around the Earth. It plays a critical role in regulating the planet's temperature by interacting with incoming solar radiation and outgoing terrestrial radiation.
Statement-wise Analysis
- Statement 1 is Correct: The atmosphere is defined as a vast blanket of air that surrounds the Earth, held in place by the planet's gravitational force. It extends for hundreds of kilometers above the surface.
- Statement 2 is Incorrect: The atmosphere does not allow all solar radiation to reach the surface. A significant portion of incoming solar radiation is:
- Reflected back to space by clouds and dust.
- Absorbed by gases like water vapour and ozone (which absorbs harmful ultraviolet rays).
- Scattered by aerosols.
- Statement 3 is Incorrect: The atmosphere prevents a sudden increase in temperature during daylight hours. Without the atmosphere, there would be no scattering or absorption of sunlight, causing the Earth's surface to become scorching hot during the day (similar to the Moon). Conversely, without the greenhouse effect to trap heat, the Earth would freeze at night. Therefore, stating it would remain frozen during the day is factually wrong; it would experience extreme heat.
Key Takeaway
Significance of Atmosphere: It moderates Earth's temperature by preventing excessive heating during the day and excessive cooling at night (Greenhouse Effect), thereby reducing the diurnal range of temperature.