# Explanations

Posts intended to clarify how things work

## What factors contribute to increases in planetary temperature?

Physics tells us there are only a few fundamental factors that drive global temperatures. It is helpful to define what I will call the “energy-balancing temperature." This is the average global temperature that the planet’s surface would need to have in order for the rate at which energy leaves the planet by escaping into space to exactly balance the rate at which energy arrives into the planet’s atmosphere, oceans, and land.

## 11+12 =23, or How I know the Greenhouse Effect is real

Recently, someone asked me, “Do you think the Greenhouse Effect is real?” I found myself answering, “I don’t ‘think’ it’s real. At this point, I know beyond any shadow of a doubt that it’s real. As real as 11+12 = 23.” I think it's about time that I spell out how I know it...

## Flow constriction: How the Greenhouse effect warms a planet

Many explanations of the atmospheric Greenhouse effect leave people unclear about how it raises the global temperature. I’d like to look at a simple fundamental principle which sheds light on how warming happens. How do you raise the level of something? If we're talking about water in a reservoir, you might think the answer is pretty simple: to raise the water level, you need to add more water—right? ...

## Energy Conservation allows Power to Appear seemingly from Nowhere (no, that doesn’t imply unlimited free energy)

Some people are surprised when they see diagrams showing that the Earth absorbs about 240 W/m² of sunlight, but the Earth’s surface radiates 398 W/m² upward and the atmosphere radiates 340 W/m² downward to the surface. "You can’t have more power than what arrives from the Sun!”...

## Why do some people think the atmospheric Greenhouse Effect violates the Second Law of Thermodynamics?

Some people assert that: The atmospheric Greenhouse Effect “can’t be real because it violates the Second Law of Thermodynamics. As a physicist, I can tell you that this assertion is absolutely wrong...

## Energy Recirculation and a Layered Radiative Atmosphere Model

I’d like to look at: energy recirculation as a way to conceptualize how energy fluxes between the Earth and its atmosphere can be larger than the incoming flux; and a model of an "atmosphere" consisting of one or more distinct layers which can transfer heat only by radiative heat transfer...

## What would you say to someone who says “The greenhouse effect can’t be real because the Second Law of Thermodynamics says something cooler can’t raise the temperature of something warmer”?

Sometimes people assert that the “greenhouse effect” can’t be true, because they believe the model involves heat flowing from a cool atmosphere to a warmer Earth’s surface, thereby violating the Second Law of Thermodynamics. Various sources of confusion seem to be present...