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Conduction is a fundamental method of heat transfer where thermal energy moves through a material or between objects in direct contact. Imagine holding a cup of hot coffee; the heat from the coffee is transferred to your hand through the material of the cup – this is conduction in action. In conduction, the faster-moving molecules of the warmer object collide with the less energetic molecules of the cooler object, transferring energy in the process.

For example, when an air parcel comes into contact with a warm surface such as the ground heated by the sun, the heat is conducted from the ground to the cooler air. The molecules within the ground vibrate more rapidly with thermal energy and as they collide with the air molecules, they transfer some of that energy, thereby raising the temperature of the air parcel.

In essence, conduction is about the flow of heat through solids or between solid objects in contact, driven by a temperature difference and the conductive properties of the materials involved.

Convection is the heat transfer method involving the movement of fluids such as gases or liquids. For a real-world illustration, consider a pot of water on a stove. As the water at the bottom warms up, it becomes less dense and rises, while the cooler, denser water at the top descends to take its place, creating a cycle called a convection current.

This same principle applies to the atmosphere. When the sun heats the earth's surface, the air in contact with the ground is warmed, expands, and becomes less dense. This lighter air rises through cooler air, just as the warm water rises through the cooler water. As the warm air rises, it may encounter an air parcel, transferring heat to it through the process of convection. Besides naturally occurring convection, there are also forced convection systems like fans and pumps that actively move the fluid to achieve heat transfer.

Radiation differs from conduction and convection as it involves transferring energy via electromagnetic waves and does not require a medium to travel through. The sun is a perfect example of a radiant heat source. Its energy travels through the vacuum of space and is absorbed by objects that it strikes, including air parcels in the earth's atmosphere.

When solar radiation reaches an air parcel, the energy is absorbed by the molecules, increasing their kinetic energy which results in an increase in temperature. Everything that has a temperature emits radiant energy, but the amount and type of radiation depend on the temperature and surface properties of the emitting object. This type of heat transfer can occur in a vacuum, which is why the Earth is able to receive heat from the sun despite the intervening empty space.