Question

Which of the following statements is/are NOT true?

• A. Urban heat island effect in a city can be reduced by increasing trees and vegetation cover in the city.
• B. Urban heat island intensity is affected by PM$_{2.5}$ concentrations in a city.
• C. Urban heat island intensity increases due to installation of reflective roofs in a city.
• D. In comparison with the non-urban areas, urban heat island effect raises night-time temperatures more than daytime temperatures in cities.

Hint:

- UHI is reduced by vegetation and reflective roofs.
- UHI is stronger at night than daytime.
- Air pollutants (PM$_{2.5}$) contribute to UHI by trapping heat.

Answer 1

The Correct Option is C

Step 1: Recall what Urban Heat Island (UHI) is.
- UHI refers to higher temperatures in urban areas compared to rural surroundings. - Caused by heat absorption from concrete, asphalt, low vegetation, waste heat from vehicles, industries, etc.
Step 2: Analyze Statement (A).
- More vegetation and trees reduce heat storage, provide shade, and increase evapotranspiration. - Hence, this reduces UHI effect. - Statement (A) is TRUE.
Step 3: Analyze Statement (B).
- UHI intensity is influenced by air pollutants (including PM$_{2.5}$) since aerosols trap heat and modify radiative balance. - Hence, Statement (B) is TRUE.
Step 4: Analyze Statement (C).
- Reflective (cool) roofs reflect solar radiation, reduce heat absorption, and therefore reduce UHI intensity. - The statement says UHI “increases”, which is opposite. - Hence, Statement (C) is NOT TRUE.
Step 5: Analyze Statement (D).
- UHI effect is stronger at night since urban surfaces slowly release absorbed heat while rural areas cool faster. - Thus, cities remain warmer during night compared to day. - Statement (D) is TRUE.
Step 6: Conclusion.
Only Statement (C) is NOT true. Final Answer: \[ \boxed{\text{(C) Urban heat island intensity increases due to installation of reflective roofs in a city.}} \]