Permanent winds that blow constantly in a particular direction.
Explanation
Trade winds are a primary component of the planetary (or permanent) wind system. Planetary winds are global wind patterns that blow constantly throughout the year in a specific direction, driven by latitudinal differences in atmospheric pressure and the Coriolis force.
Option Analysis:
- Winds that blow only during the day in coastal areas. is incorrect: Winds that blow only during the day in coastal areas describe Sea Breezes. These are local winds caused by the differential heating rates of land and water bodies.
- Permanent winds that blow constantly in a particular direction. is correct: Trade Winds are permanent winds that blow constantly in a particular direction. Specifically, they blow from the Subtropical High-Pressure belts (approx. 30°N and 30°S) towards the Equatorial Low-Pressure belt. They are known as the North-East Trade Winds in the Northern Hemisphere and South-East Trade Winds in the Southern Hemisphere.
- Winds that bring rain to the entire Indian subcontinent in June. is incorrect: Winds that bring rain to the Indian subcontinent in June are the South-West Monsoons. These are periodic or seasonal winds characterized by a complete reversal of direction between seasons.
- Hot and dry winds blowing in the northern plains of India. is incorrect: Hot and dry winds blowing in the northern plains of India refer to the Loo. These are local winds that occur specifically during the summer months.
Key Takeaway:
Trade winds are permanent planetary winds that flow steadily from the subtropics toward the equator throughout the year, unlike seasonal monsoons or local breezes.