Convection

Convection in meteorology

La convection It is a process that occurs in nature by which heat is transferred between liquid, gaseous or liquid substances with liquid, solid and liquid, etc. All these combinations are possible when we talk about this heat exchange process in which both bodies, regardless of the state in which they are, will have different temperatures. Convection is an important process in meteorology that involves a transfer of heat between air masses.

Do you want to know more about convection? In this article we will explain everything about it.

Heat transfer

Convection in a pot

Heat transfer is the main thing in convection. It does not matter the state of each body, As long as there is a noticeable temperature difference, convection can occur. This is a process that we take advantage of to heat the water in a pot. When two bodies at different temperatures meet, what we know as heat flow takes place. It is the body with the highest temperature that transfers the heat to the least.

This is one of the reasons why, when we put our hand near the stove, we feel the heat. The stove is not transferring that heat. There are also other heat transfer processes such as radiation and conduction that are explained in conjunction with convection, so we will also review them later.

Both liquids and gases are considered fluids. The movement of its molecules is responsible for the heat being able to establish a flow between the two bodies. Poor thermal conductivity means that the dough has to be forced to extract or give heat. To do this, it cools or warms solids or liquids.

A heat exchanger is used in the boilers. This consists of a metal pipe where water circulates inside. Outside we will have gas at a very high temperature. Through the convection process, the gas will be able to give up its heat to the metal tube and the water will receive it by conduction. The tube heats up and gives up heat to the water flowing in the other direction. This water, receiving heat by convection, heats up to become steam.

Driving

Driving

One of the most frequently discussed topics when it comes to energy is both direct and indirect heat transfer. In household electrical appliances we use heating and air conditioning to transfer heat or cold. These appliances also have their energy losses. The global between the amount of energy we use and that we lose qualifies as energy efficiency and it is an important variable to take into account in the final price of a product.

Driving is the process that is easily understood by everyone. Is about a heat transfer between two points that are at different temperatures. This transfer occurs without there being an exchange of matter between them. A simple example is: we have a metal bar in which one end is at 80 degrees and the other at room temperature. If there is no other external influence, conductive heat transfer will occur from the hot end to the cold end. This will cause the cold end to heat up. What to say that driving depends entirely on the type of material we are talking about. It is not the same to speak of a metal bar than a wooden one. Conductivity is an element to take into account in this physical process of energy exchange.

Radiation

Radiation

Another process by which heat is exchanged is radiation. We also use it heavily in the home. It is the heat that a body emits because of its temperature but without even contact between the bodies. We saw that in conduction there must be friction between bodies or extension of heat through the same body. What could not have was matter exchange. In this case, the warmer body can warm to the cold without even touching it.

In this type of process we will see a heat exchange by the simple fact that a body is hotter than another. For this process to be perceived, it is necessary for the warmer body to be at a very high temperature. A simple example of this can be seen in summer when you go to the beach. When you leave the car parked and the hours go by, you come back to get something and when you touch the metal of the doors you burn from how hot it is. The Sun is at a very far distance and, however, by radiation it is able to transfer that heat to the car.

In the case of radiation we also take into account the type of material we are dealing with. A wooden surface heats up but is unable to store as much heat due to its insulating properties.

Types of convection

Convection rains

Once we have explained the possible heat transfers that exist, we are going to count the types of convection that exist. Heat transfer by convection can occur in several ways and they are:

  • Forced: It is carried out through a fan, in the case of air, or a pump, in the case of water, in which the fluid moves through a hot zone and heat is transported to a cold zone.
  • Natural: occurs when the fluid extracts heat from the hot zone and modifies its density. This causes it to move towards the coldest area where it will give up its heat.

To better understand the different types of convection we are going to give an example. If we turn on a radiator, we have to wait for the temperature to increase. If we put our hand on the radiator at a short distance, we will see that there is a totally natural air flow, since hot air tends to rise. The surrounding air heats up and decreases in density, making it weigh less. Thus, it flows upwards causing the air to pass through again, continually renewing itself. It is as if it were a cyclical process.

I hope that with this information you can learn more about convection and heat transfer.


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  1.   Freddy said

    Hi. I just read the good article on convection. An illustration of a campfire is included and what would be the transfer of heat by RADIATION, CONVECTION AND CONDUCTION. The realization of the transfer by radiation and conduction I understand it perfectly, what is difficult for me to visualize is the difference between RADIATION and CONVECTION. I do not see difference between one and the other, except that one goes upwards while the radiation towards the side. The two forms would not be by convection or radiation?
    Should I understand that convection is ALWAYS up and not sideways?
    I appreciate any comments that help me understand this.
    I thank you in advance for your time and good disposition.
    Best regards