Old 14th Oct 2019, 16:36
  #26 (permalink)  
Ian W
 
Join Date: Dec 2006
Location: Florida and wherever my laptop is
Posts: 1,314
Originally Posted by StraightLevel View Post
Some interesting responses and links, however it still looks to me like there is a vast vast amount that science and certainly us don’t know about the climate and how it gets influenced both naturally and by us as a species.

There was some interesting info provided in one of the links that states that CO2 lasts in the atmosphere for years while H2O only lasts for a mater of days which I found very interesting. This could be a very significant difference between hydrogen and carbon based fuel exhaust emissions which could possibly warrant further scientific study.

At the risk of appearing stupid, I think it’s very easy to overly simplify things by saying that on a cloudy day it’s warmer and vice versa, however that’s not always the case. On a cloudy day during the day it blocks some sunlight and keeps the earths surface and therefore local atmosphere cooler, however at night a cloud layer insulates and keeps the air warmer.

Thinking completely outside the box, maybe rather than ban flying on certain days maybe it would be better to ban night flights when contrails could keep the atmosphere warm.

I hope that most of us on this forum want to continue having the benefits of flying, and aviation is a unique form of transport in the way that we go up into the upper atmosphere rather that stay on the earths surface.

I just hope that science will find a way for this to be turned into an advantage as opposed to the perceived negative that it is at the moment in certain circles.
There was some interesting info provided in one of the links that states that CO2 lasts in the atmosphere for years while H2O only lasts for a mater of days which I found very interesting. This could be a very significant difference between hydrogen and carbon based fuel exhaust emissions which could possibly warrant further scientific study.
A turning propeller blade in only there intermittently but a wall stays in place permanently therefore ......

The thing with water (the hydrologic cycle) is that it is continually being replaced at a huge rate. The hydrologic cycle is very powerful so for example in extremes a Cat 3 type hurricane in a day dissipates as much energy as 200 times the daily world electricity generation capacity . Another way of seeing it is that a hurricane releases more than a megaton yield nuclear weapon every 10 seconds imagine the amount of energy from a frontal system across the entire US. All this is convective energy is based on latent heat release by water molecules and becomes radiant energy and leaves to space. The atmosphere contains very little energy compared to the oceans with the top 6 meters or so of the oceans having a heat content that is more than the entire atmosphere. It is the continual evaporation that maintains the humidity of the atmosphere and cools the surface of the oceans as does transpiration from plants. There is a hypothesis that as the atmospheric and ocean temperatures rise this causes more convective clouds and the clouds are not only evidence of evaporative/convective cooling but also raise the albedo reflecting solar radiation back to space. (Sometimes called the Iris Hypothesis)
It does appear that there is more correlation between atmospheric temperatures and the solar activity - we will find that out in the next decade or so as even NASA is expecting some cooling from the quiet sun

There are two things to be concerned about with graphs watch what is being done with the Y axis normally this exhibits a degree (cough) of precision in temperature measurement that would not be achieved by the accuracy of a met observer in howling sleet reading a temperature from a thermometer in a Stevenson Screen. The comparisons with 'global temperatures' from the past when in the Southern hemisphere a hundred years ago there were very very few observations - are extremely shaky as the much of the temperatures are based on guesswork but then expressed with a precision of hundredths of a degree (ever seen error bars on those graphs? No nor have I),

The other issue is correlation and causation all that can really be said is that if there is NO correlation between one value and another then there probably isn't causation. But two values closely correlating over a period definitely does not mean there is causation - see https://www.tylervigen.com/spurious-correlations

We are currently at the cold end of the Holocene - there is nothing special about the temperatures or their variance. So I wouldn't sell your coats. Definitely I wouldn't limit aviation as it is the most efficient transport in terms of miles per gallon per paying passenger. Work it out you'll find in those terms an A320 (and most other aircraft) has better consumption than a Prius and doesn't need road infrastructure between departure and destination.

Last edited by Ian W; 14th Oct 2019 at 16:42. Reason: spelling
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