AFound up to 120 km
BConcentrated in the exosphere
CPresent only up to 90 km altitude
DUniformly distributed across all layers
Answer:
C. Present only up to 90 km altitude
Read Explanation:
Correct Answer: Option A) Found up to 120 km
Water vapour is one of the most important components of the atmosphere, and its distribution varies significantly with altitude. Here's a detailed explanation of water vapour distribution in the atmosphere:
Vertical Distribution of Water Vapour:
Water vapour is not uniformly distributed throughout the atmosphere. Its concentration decreases rapidly with altitude due to several factors:
Temperature Effect: As altitude increases, temperature generally decreases, reducing the atmosphere's capacity to hold water vapour.
Pressure Effect: Lower atmospheric pressure at higher altitudes means less dense air and reduced water vapour content.
Source Limitation: Most water vapour enters the atmosphere through evaporation from oceans, lakes, rivers, and transpiration from plants at the Earth's surface.
Distribution Pattern:
Troposphere (0-12 km): Contains about 99% of all atmospheric water vapour. The highest concentration is near the surface, decreasing exponentially with height.
Stratosphere (12-50 km): Very little water vapour present due to extremely low temperatures.
Mesosphere (50-85 km): Minimal water vapour content.
Thermosphere (85-600 km): Water vapour can be found in trace amounts up to 120 km altitude, though in extremely small concentrations.