Question

Which remote sensing is capable of penetrating through the cloud?

• A. Thermal
• B. Optical
• C. Optical and Near-Infra red
• D. Microwave

Hint:

Microwave remote sensing is also capable of operating at night (day-night capability) because it often provides its own source of energy (active sensing).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Remote sensing uses the electromagnetic (EM) spectrum to observe the Earth's surface. Different wavelengths interact differently with atmospheric constituents like water vapor and clouds.

Step 2: Detailed Explanation:
Optical (Statement 2), Near-Infrared (Statement 3), and Thermal (Statement 1) sensors operate at relatively short wavelengths (typically 0.4 to 14 micrometers).
These wavelengths are easily scattered or absorbed by water droplets and ice crystals in clouds. Therefore, these sensors cannot "see" through cloudy weather.
In contrast, Microwave sensors (Statement 4) operate at much longer wavelengths (ranging from 1 mm to 1 m).
These long wavelengths are not scattered by small atmospheric particles. This allows microwave radiation to penetrate through clouds, fog, haze, and even light rain.
This "all-weather" capability makes microwave remote sensing (particularly Active Radar like SAR - Synthetic Aperture Radar) indispensable for monitoring regions that are frequently cloudy, such as the tropics or coastal zones.

Step 3: Final Answer:
Microwave radiation has the unique property of penetrating clouds, making it suitable for all-weather remote sensing.