Why do you think that clouds and water vapor act like insulators from the sun

Water vapor is a green house gas which absorbs the heat radiated from the earth's surface and keeps the earth warm. Clouds are formed by the condensation of water vapor in the atmosphere. They shield the earth from the sun by reflecting or scattering the solar energy and also trap the heat from the earth's surface. Thus both clouds and water vapor act like insulators from the sun and warms the planet.

Explanation:

When the earth’s surface get heated by the sunlight, some of the heat radiates back into the atmosphere and most of this heat is absorbed by gases in the atmosphere called green house gases. This process is called greenhouse effect, which keeps the earth warm.  The green house gases mainly consists of carbon dioxide and water vapor.

Water vapor is formed through a process called evaporation. In this process, water from the ocean, rivers, and lakes evaporates to become water vapor using the energy from the sun. Water vapor also moves into the atmosphere by transpiration (plants) and sublimation (snow and ice).

The water vapor cools down and transforms into water droplets by a process called condensation, as it rises high in the atmosphere where the air is cooler. This water droplets that formed by condensation make up clouds. Low, thick cumulus clouds reflect majority of the solar energy straight back into space and thus cool the earth. High, thin cirrus clouds scatter the solar energy within the atmosphere and also trap the heat emitted by earth, thus warming the planet. Thus both clouds and water vapor act like insulators from the sun and warms the planet.