Convection is the transfer of heat from
a. warmer objects to cooler objects in liquids and gases.
b. cooler objects to warmer objects in liquids and gases.
c. cooler objects to warmer objects by direct contact.

warmer objects to cooler objects in liquids and gases

The natural convection is a process, in which the fluid movement occurs from heat transfer. When a fluid is warmed or chilled, its density changes and the buoyancy effect create a natural flow in the affected region, which makes itself the rise of hotter fluid and the fall of cooler fluid: hence, energy transfer from hotter area to colder area and such process is repeated as long as the temperature variation in fluid exist.

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation: