Key Points

Heat is transferred from a hotter region to a colder region through three distinct processes: conduction, convection, and radiation.

Conduction is the transfer of heat through direct contact, primarily in solids. In this process, particles transfer energy to adjacent particles without changing their own positions.

Materials like metals that allow heat to pass through them easily are called good conductors. Materials like wood, glass, and air that resist heat flow are called poor conductors or insulators.

Convection is the mode of heat transfer in liquids and gases, involving the actual movement of particles. Hotter, less dense fluid rises, and cooler, denser fluid sinks, forming a convection current.

During the day, land heats up faster than water. The warm air above the land rises, and cooler air from the sea moves towards the land to take its place, which is called a sea breeze.

At night, land cools down faster than water. The warmer air above the sea rises, and cooler air from the land moves towards the sea, creating a land breeze.

Radiation is the transfer of heat through electromagnetic waves, which does not require any medium. The heat from the Sun reaches the Earth through this process.

Dark-colored surfaces absorb more heat radiation than light-colored surfaces, which reflect most of the heat. This is why we wear dark clothes in winter and light clothes in summer.

Air is a poor conductor of heat. Woollen clothes and hollow bricks trap air, which acts as an insulator to keep us warm in winter and houses cool in summer.

The water cycle is the continuous movement of water on Earth, driven by the Sun's heat. It involves evaporation, condensation, precipitation, and collection.

The Sun's heat causes water from oceans and lakes to evaporate into water vapor. This vapor rises, cools, and condenses to form clouds.

Infiltration is the process of water seeping into the ground through soil and rocks. This water gets stored underground as groundwater.

An aquifer is an underground layer of rock or sediment that holds groundwater. This is the source of water for wells and bore wells.

Water seeps fastest through materials with large spaces like gravel, slower through sand, and slowest through materials with small spaces like clay.