The reason why the Yangzi is warmer than the Yinzi is because the sun’s energy travels across space in the form of electromagnetic waves without a medium to reach Earth and heat objects, which can be explained by understanding the nature of heat and light.
Why is the Yangzi warmer than the Yinzi? No matter how hot the sun is, how can it travel across space without a proper medium to heat objects on Earth? To understand this, we first need to be clear about the nature of heat and light.
Historical understanding of heat
Until the mid-18th century, scholars thought that heat was the work of some invisible substance – a “heat element” – and that the melting of a solid or the evaporation of a liquid was a type of chemical reaction between the heat element and the particles that make up the solid or liquid. However, thanks to the work of Rumford, Meyer, Joule, and others, the existence of heat element was denied and the concept of heat energy was established instead. It was Clausius who specifically clarified the identity of heat, arguing that the thermal energy of a gas is the kinetic energy of the gas molecules, and therefore the temperature is a measure of how fast the gas molecules are moving. Furthermore, Maxwell showed that the speed of motion of gas molecules at a constant temperature varies around a mean value, so heat is the “average kinetic energy of the particles that make up an object. The particles of any object are in constant oscillatory or rotational motion around a mean position, and temperature is the magnitude of this kinetic energy.
Electromagnetic theory and light
To understand the nature of light, we also need to understand electromagnetic theory, because light is a type of electromagnetic wave. The existence of electromagnetic waves was deduced through the experiments of Enfer, who showed that electric currents (electric fields) produce magnetic fields, Faraday, who confirmed that magnetic fields produce electric currents, and Maxwell’s theory that synthesized them. Anfert showed that a magnetic field is created by passing an electric current through side-by-side wires, and that a cylindrical coil of wires – called a solenoid – becomes a strong magnet when a current is passed through it, while Faraday showed that a magnet, when passed through a coil with no current, produces an electric current from changes in the magnetic field of the magnet. An electric field produces a magnetic field, which in turn produces an electric field. Maxwell summarized the results of these experiments and formulated a theory called Maxwell’s equations, from which the existence of electromagnetic waves can be deduced.
How electromagnetic waves propagate
If you suddenly pass a current through a wire or change the strength of the current, a magnetic field is created around it, which creates a secondary electric field, which in turn creates a secondary magnetic field. The electric field creates a magnetic field, which creates an electric field, which creates a magnetic field, which creates an electric field, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on, and so on. Unlike mechanical waves, which are actual vibrations of matter, like sound, light is an electromagnetic wave that propagates through successive changes in electric and magnetic fields. Later, scientists confirmed that electromagnetic waves propagate without a medium, explaining why sunlight can travel across the void of space.
Propagation of solar energy and its transfer to Earth
What comes from the sun are not particles of heat, but electromagnetic waves, which, when they hit an object, interfere with it with vibrations. These vibrations then interact with the particles of matter, causing them to move, which in turn raises the temperature of the matter. This is how the sun’s light is able to travel through space without any intermediary and heat objects on Earth.
The difference between positive and negative temperatures
The difference in temperature between the positive and negative solstices can be explained by this principle. On the positive side, the sun’s electromagnetic waves directly hit objects, actively vibrating their particles and raising their temperature. On the other hand, this doesn’t happen because the sun’s light doesn’t reach them directly, and they stay relatively cool. Furthermore, different colors and properties of objects absorb solar energy to different degrees, so the surface temperature of an object can vary even in the same sunny location. For example, darker-colored objects absorb more of the sun’s energy and heat up faster, while lighter-colored objects are more reflective and therefore warm up less.
Conclusion
Thanks to these principles, we can understand that the sunny side of the sun is warmer than the negative side. The sun’s energy is transmitted in the form of electromagnetic waves, which travel across space without a medium to heat objects on Earth, and the sunny side is warmer because the light hits it directly. The process of understanding natural phenomena through these scientific principles is fascinating and provides a deeper understanding of phenomena that we can easily observe in our daily lives.
