Global Warming - the basic principles


This is a big, important and timely subject.  Sea levels, melting ice, severe storms, hurricanes, crop, temperatures, and rainfall are some of the weather phenomena that are tied to the prospect of global warming. And like all predictions, the truth  (verification) isn’t certain until the future. It seems to have become politicalized. One of the problems in this debate is that both sides of the polarization have picked and chosen the data to support their conclusions. We see the truth only dimly now.

First, it is important to know what is meant by climate.  Here, it is simply a long-term change in the average weather.  Weather, the daily environment we are aware of (hot, cold, rain, etc.) is notoriously variable on a day-to-day basis.  But there are predictable changes, such as hotter in the summer than the winter, and dryer in the deserts than the tropics.  Those are climate variables.  When we speak of Global Climate Change we mean that everywhere on earth the average temperature for all seasons will be getting warmer with all the attendant changes that accompany weather.  But it does not necessarily mean that it will be uniformly warmer.   

Crucial to the understanding, I will have to lay some groundwork of how and why we experience temperature.  In the interests of clarity and simplicity, I will do some violence to some fascinating (to me) details. 

Before going any further, lets consider an analog of how the earth is warmed with the accompanying illustration.

Hurricane activity is distributed about nearly the Autumnal Equinox, not when the sun is highest in the sky. This can also explain why it is hotter at 5pm than when the sun is directly overhead at noon, as well as why hurricanes are at a maximum at the Autumnal Equinox  and not when the sun is highest in the sky at the Summer Solstice. 

At the top of the can of water is a hose that represents sunlight.  The water comes in and starts to fill up the tank.  But there is a spigot at the bottom that lets the water out.  The deeper the water in the tank the greater the pressure at the bottom and the more the water is forced out the bottom of the tank.  Eventually the water in the tank will reach an equilibrium level where the water leaving the tank equals the  water coming in. 

The water coming in represents the sunlight and the water leaving represents out going radiation and the level of the water in the tank represents the temperature. Lets first look at it for a single day.

The hose at the top start to input water at sunrise and the temperature (depth of water) rises.  At noon, the water flowing in is at its fastest rate.  After noon until dusk it is slowly shutting down.  Mean time, the water flowing out of the spigot at the bottom (representing the earth radiating out to space), is open 24 hours a day.  It actually radiates the most when the water level, representing the temperature, is the highest. As long as the water coming in is greater than the water leaving level will increase.  Incoming and out coming are equal in the mid-to-late afternoon, which explains why the temperature is the hottest in mid-to-late afternoon. After late in the afternoon not much sunlight is coming in and yet the outgoing radiation keep cooling and that continues until day break.  The water level (temperature) continues to drop all night long as the earth continues to radiate out to space. Seasons follow much the same logic, for as you go toward the poles the flow of water (sunlight) is not as strong and is “on” for a shorter and shorter time depending on the day of the year so the temperature is cooler.

Next – how this relates to global warming and hurricanes.