Overview of RTC and HTC – why we need
both
Gerald Ratzer
February 3, 2025
This research forms the background and foundation for our current position.
RTC – the Radiative Transfer Concept has been well studied and forms the basis the Greenhouse Effect (GHE). HTC is the Heat Transport Concept and is essential to understand how the heat that arrives via photons from the Sun is converted into heat that is then moved from the Tropics to the Poles. HTC is required to cool the Earth. At the Top of the Atmosphere (TOA) the energy in and out has to be similar, but not in complete equilibrium. A chart of the Earth’s temperature does rise and fall – with peaks and valleys, which is a sign that the energy in and out is not perfectly balanced.
The main source of our energy is the Sun, which emits energy as photons, that travel at the speed of light, through space. These photons vibrate over a wide range of frequencies (colours). At the Top of the Atmosphere (TOA) about 1,366 watts/m2 of energy arrive. The albedo is 0.30 or about 30% of the incoming sunlight is reflected, mainly by clouds. Of the energy that arrives at the surface about 2/3 cools by local heat and 1/3 by emitting radiation, mainly through the “Atmospheric Window”.
When an individual photon arrives at or near the Earth’s surface, it can be scattered or absorbed by the dense, moist surface air. This process is called thermalization and converts the photon energy to heat energy. HTC or the Heat Transport Concept is the second part of understanding the internal processes of our weather and climate. HTC is just classical physics, governed by the four Laws of Thermodynamics. These are taught in high school and are much easier to understand than the quantum mechanics needed for RTC.
February 3, 2025
The important air molecules are Nitrogen, Oxygen and Water Vapour. The optical depth/transparency at the surface is very opaque to photons. In the upper atmosphere, an excited air molecule can relax – by spontaneous emission and emit a new photon – in any direction. In the Troposphere this new photon will be quickly thermalized again and only if it is as high as the Mesosphere, near the TOA, will it really escape to space.
Once a photon has been thermalized – its energy is now heat. The heat of a gas is the average kinetic energy of the molecules. Heat moves with a medium (gas, liquid or solid) by a few processes, namely - Conduction, Convection, Evaporation, and Gravity. In the Troposphere the important one is Convection from the surface – up. In the Tropics, much of the sunlight energy is used to evaporate water. This phase change from Waterto-Water Vapour (WV) must overcome the Latent Heat of evaporation of 2,454 kJ/kg at 20°C. The warm moist air is buoyant and moves upwards, against gravity, to the dew point where condensation takes place, releasing heat for more upward travel. This upward rise is a gain in potential energy for the warmed gas molecules. Once they cool down, gravity will pull them down to the surface – an important process to see that our atmosphere does not spin off into space! Potential energy is converted by gravity to kinetic energy, which heats the molecules on the way down.
The atmospheric winds and the oceans are the main ways to transfer heat from the Tropics to the poles. There is about 1,000 times more heat capacity in the oceans than in the air. For instance, the heat capacity of the oceans can accommodate the energy from a thousand days or more of solar energy. The ocean currents are the major way to transport heat to the poles. The Gulf Stream moves slowly at ~4 knots and keeps Scandinavia ice-free. The trade winds, jet streams and Hadley cells move heat as well.
Under the oceans, there are many volcanoes which heat the oceans. Hunga Tonga was a submarine volcano, which blasted a huge amount of water into the Stratosphere, which warmed Earth for some 3 years. These submarine volcanoes give rise to El Niño and the “Warm blobs” in the Pacific and Atlantic.
So, there are many aspects to the complex process of converting the Sun’s energy in the visible frequency range into heat and how this heat is distributed around the Earth to cool it. Our latest paper with Douglas Lightfoot entitled “The Sun Evaporates Water to Cool the Earth for Life to Flourish” covers more details on HTC.
https://doi.org/10.29169/1927-5129.2025.21.03
Gerald Ratzer Professor Emeritus McGill, Montreal