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September 18, 2021

Benyamin Amiri

By: Benyamin Amiri


Reading time: 11 min

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In this lesson, we will learn about the difference between temperature and heat, Temperature measuring units in aviation, and finally, consider the types of heat transfer.


The Earth’s main source of energy is the sun. All atmospheric phenomena such as the formation of clouds, wind, storms, etc. are due to energy from the sun.

The amount of solar energy that reaches the earth as it passes through different layers of the atmosphere is called insolation.
This energy has different wavelengths called solar spectra, which are:

  • Radiowave
  • Microwaves
  • Infrared Radiation
  • Visible Light
  • Ultraviolet Radiation
  • X-Ray
  • Gamma Ray
  • Cosmic Ray

Wavelengths of visible and non-visible light

Wavelengths of visible and non-visible light


Temperature measuring units

The units of temperature measurement that are commonly used in daily life are:
Kelvin (K)

The main unit of temperature in the International System of Units (SI) is Kelvin and its symbol is K.

Normally, for daily applications, the Celsius scale is used, which 0 ° is the freezing point of water and 100 ° is the boiling point of water at sea level.

In United State, Belize, Myanmar, and Liberia the Fahrenheit scale is used for most temperature measuring purposes.

In aviation, two scales of temperature, Celsius and Fahrenheit are used, so the following formulas can be used to convert these two units into each other. Also, you can use temperature conversion here.

To convert Celsius to Fahrenheit, we use the following formula:
F = (1.8 C)+32

To convert Fahrenheit to Celsius, we use the following formula:
C = 1.8 (F-32)

temperature conversion


Temperature definition

The average kinetic energy of a material or system is called temperature, measured by Celsius, Fahrenheit, or Kelvin.

Heat definition

Heat describes the transfer of heat energy between molecules within a system or an object and is measured in joules and expressed in numbers.

Types of heat transfer


This type of transmission is caused by changes in electromagnetic fields in different directions. The higher the source heat, the shorter the wavelength. Therefore, the waves emitted from the sun have short wavelengths.



In this case, energy or heat is transferred by the material without the material itself being transferred.
For example, if we heat the end of one wire by fire, the other end of the wire will heat up after a while. The air adjacent to the earth is heated during the day by conduction and cooled by the same method during the night.



This type of energy transfer occurs vertically due to the movement of matter.

For example, if we turn on a lamp, the lamp starts to heat up and the air around it also heats up, which causes the heated air to move upwards and transfer heat energy to higher parts.

It should be noted that the physical properties of objects are important in this energy transfer.
For example, the beach heats up and cools down faster than the sea, or the air on the runway gets hotter and colder than the air in green areas such as grass and trees.
This inconsistency in the type of objects causes the transfer of energy vertically, which in aviation causes the formation of clouds and atmospheric disturbances such as turbulence.
Radiation Convection conduction


When cold air moves downwards due to its greater concentration and weight, warm air replaces it, which results in a horizontal movement called advection, which can be seen in the figure below.

The most important result of this energy transfer is wind production.


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