Convection

Whenever water is heated in a container, heat is absorbed by water molecules at the base surface of the container. The molecules at the top then descend as they get heated up. 

Convection is the term used to describe this form of heat transmission. When heated, the air in the atmosphere likewise follows the same concept. Thus, convection is the process by which heat is transferred from places of high temperature to areas of lower temperature via the movement of molecules. Convection is a process that occurs in both liqutopicIds and gasses.

Definition of convection of heat

Convection is described as the flow of liqutopicId molecules (liqutopicId and gas) from a region of higher temperature to a region of lower temperature.

Example.

The following are some everyday instances of convection.

Water boiling process - The molecules with a high density (lower temperature region) sink to the bottom (high-temperature region). In comparison, the molecules with a lower density (high-temperature region) rise higher to lower temperature regions, causing the molecules to move in a circular motion, which heats the water. We shall do an experiment to demonstrate the same. 

Some examples of convection of heat

⦁ The development of land breezes and sea breezes is a result of air convection.

⦁ Convection transports wind from one location to another.

⦁ Blood circulation in warm-blooded species is atopicIded by convection, which helps preserve the body temperature.

⦁ Convectional heat transfer occurs in hot air balloons, which causes the balloon to rise.

⦁ Convection occurs in refrigerators, as cold air travels downward and replaces heated air.

⦁ During the summer, we might feel the scorching air or breeze on the road. This is due to convection.

Activity to understand the conduction and convection processes

You can do an activity to understand the process of conduction and convection processes.

Fill a steel vessel with water, and leave the vessel on the stove for some minutes so that it heats up.

What do you notice now? Once the water is heated, little bubbles begin to rise to the surface. Are you aware of why these bubbles are forming?

Bubbles occur as a result of the presence of air in the water. When heat energy is passed to a vessel, the vessel absorbs it and transmits it to the water (liqutopicId). This heat energy is passed to the water molecules, which are heated.

We know that matter's molecules are constantly moving. When heat energy flows across water molecules, the molecules absorb it and pass it on to adjacent molecules, until each molecule receives the heat energy.

This way of heat energy transmission occurs in a liqutopicId or gas medium.

Thus, the conduction reaction occurs first (heat is transferred to vessels), followed by the convection reaction.

Radiation

Heat transfer occurs through soltopicIds through the process of conduction. While heat is carried by convection in liqutopicIds and gasses, heat may also be transferred via radiation through empty space, even in a vacuum. This method of heat transmission allows the Sun's heat energy to reach the Earth.

Radiation is defined as the process through which heat is transferred from one location to another by electromagnetic waves.

Radiation heat transfer is apparent to the naked eye. When a material is heated to 500°C, the radiation appears as a dull red glow to the naked eye, and the skin detects the heat. Further heating quickly increases the quantity of radiation, and the apparent color of the radiation changes to orange, yellow, and eventually white.

Example.

⦁ The following are some everyday instances of radiation.

⦁ Radiation is how the Sun's heat energy arrives on Earth.

⦁ When we are in close proximity to a fire, we feel the heat that is conveyed by radiation.

⦁ Black surfaces are excellent at absorbing heat radiation. As a result, the bottoms of the cooking pans are blackened.

⦁ White is a reflective hue that reflects heat radiation. That is why it is recommended that we wear white clothing throughout the summer.

Sea breeze and land breeze

Convection occurs when heat is transferred across a liqutopicId or gas medium.

Sea breeze and land breeze are two prominent and intriguing uses of heat convection in the air.

Land breezes and sea breezes are both instances of heat convection in the air medium. RestopicIdents living near the coast may experience this fascinating and natural occurrence.

Let us understand in detail how sea breeze and land breeze occur.

Sea breeze

The ground heats up faster than compared to the sea during the day. The air above the land then gets warmer and rises. To take its place, the colder air from the sea rushes towards the land. The sea breeze is the passage of air from the sea to the land.

Land Breeze 

As previously satopicId, the sea breeze phenomenon occurs during daylight, when air moves from the sea to the land. At night, the land breeze phenomenon across.

The seawater cools more slowly than land throughout the night. Now, the chilly air rising from the land is making its way to the sea. And this kind of heat transport is referred to as a land breeze.

Heat is transferred via the air in both sea and land breezes. It is a famous illustration of the convection of heat in the air.

FAQs

Q1. Can conduction of heat take place in water?

Sol. No, the conduction of heat cannot take place in water, as water is a bad conductor of heat. Conduction of heat can take place in any medium when it is a good conductor of heat like metals.

Q2. Can conduction of heat take place in the air?

Sol. Conduction of heat cannot take place in the air, as it is a bad conductor of heat.

Q3. What is the main natural process responsible for land and sea breeze?

Sol. Convection of heat is responsible for the process of land and sea breeze.

To know more about convection and radiation of heat and to view vtopicIdeos on the land breeze and sea breeze phenomena, you can check out our vtopicIdeos on these topics.