The correct option is 2 only
Explanation
Dust particles, also known as aerosols, are solid particles suspended in the atmosphere. They originate from sources such as sea salts, fine soil, smoke-soot, ash, pollen, and disintegrated meteors. Their distribution varies significantly based on altitude, latitude, and weather conditions.
Statement-wise Analysis:
- Statement 1 is Incorrect: Although dust particles originate at the surface, strong convectional air currents can transport fine particulates to great heights. This vertical movement allows dust to act as hygroscopic nuclei for cloud formation at various altitudes.
- Statement 2 is Correct: Dust particles are generally concentrated in the lower layers of the atmosphere. Since they are heavier than atmospheric gases and originate from the Earth's surface, gravity restricts the majority of these particles to the troposphere near the ground.
- Statement 3 is Incorrect: Higher concentrations of dust particles are found in subtropical and temperate regions due to dry winds. In contrast, equatorial regions have lower concentrations because frequent rainfall and high humidity wash out these particles from the atmosphere.
Key Takeaway:
Dust particles are most abundant in the lower atmosphere of dry, subtropical regions. They are scarce in equatorial regions due to the cleansing effect of heavy rainfall.