Cloudy nights are warmer compared to clear cloudless nights, because clouds

The correct answer is Option 2.

The phenomenon of warmer cloudy nights is explained by the greenhouse effect of the atmosphere. During the day, the Earth's surface absorbs solar radiation. At night, the Earth cools down by emitting this energy back into space in the form of long-wave terrestrial radiation.

• Why Option 2 is correct: Clouds act as a physical barrier. They are composed of water vapor and droplets that are effective at trapping terrestrial radiation. Instead of allowing the heat to escape into the upper atmosphere, clouds reflect and radiate this heat back toward the Earth's surface, maintaining higher temperatures.
• Why other options are incorrect: Option 1 is scientifically inaccurate as "cold waves" do not descend from the sky in this context. Option 3 is wrong because clouds do not "produce" their own heat; they only redistribute existing energy. Option 4 is less precise than Option 2 because the primary mechanism is the reflection/re-radiation of terrestrial heat rather than simple atmospheric absorption.