Correct Option
The correct option is (a).
Explanation
Atmospheric pressure is the weight of the column of air at any given place and time. It is influenced by altitude, temperature, and the earth's rotation. The distribution of atmospheric pressure determines wind patterns and weather conditions.
Statement-wise Analysis
- Statement 1 is Correct: Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface. As altitude increases, the column of air above a specific point decreases in mass, and the density of air reduces. Consequently, air pressure is highest at sea level and decreases rapidly with height.
- Statement 2 is Incorrect: Although the weight of the air column is significant (approximately 1 kg per square centimeter at sea level), humans do not feel this weight heavily. This is because air exerts pressure from all directions, and the internal pressure within the human body counterbalances the external atmospheric pressure.
- Statement 3 is Incorrect: There is an inverse relationship between temperature and pressure in a localized setting. In areas where the temperature is high, the air heats up, expands, and rises. This upward movement of air creates a low-pressure area, not a high-pressure area. Conversely, low temperatures cause air to cool, contract, and sink, creating high-pressure areas.
Key Takeaway: Atmospheric pressure decreases with an increase in altitude. Thermally induced pressure systems follow the rule that high temperature leads to low pressure (due to rising air), while low temperature leads to high pressure (due to sinking air).