oroboros
New Member
About a year ago I wrote this for a local news website that has since disappeared from the Internet. I dug it back out of my working copy tonight for use in this apparently hopeless Facebook argument (since deleted by the page owner... I was so kind and courteous, and even gave tips on improving his/her arguments).
Here's hoping the copy/paste from Google Docs preserved all the links intact...
The word chemtrail is short for "chemical contrails" and refers to a conspiracy theory that some combination of chemical and biological agents is being deliberately sprayed from airplanes, usually over populated areas. I first learned about this threat last summer when a friend told me about her deep fears for her children’s health. She explained that chemtrails could be any number of things, including a secret U.N. plot involving mind control or possibly even population control.
I did a little research and learned more about a wide variety of chemtrail conspiracies that are only loosely related to each other. Google has indexed more than 1.5 million pages that mention the word. One popular version of the conspiracy theory holds that they are part of so-called geo-engineering experiments designed to reverse global warming. Another version claims that chemtrails are designed to create an electromagnetic shield that protects our electronics from disruptions. Over at chemtrailagenda.com I learned that I'm living in the brave new world of toxic barium skies, weather control, mind control and population control through the use of chemtrails modulated with electromagnetic frequencies generated by HAARP. NaturalNews.com recently published Chemtrails are now a deadly fact (strangely their headline is also labeled ‘opinion’ in parentheses). From that article I learned that the government program to blame for chemtrails is called Atmospheric Radiation Measurement (ARM). NaturalNews.com helpfully offers to sell me an herbal remedy to keep me safe from the effects of chemtrails.
My friend Larry is a scientist who has worked with ARM periodically over the years and he describes their mission and methods better than I can:
ARM is a DOE facility with the mission to conduct measurements and support research into better understanding the effects of clouds and aerosols on radiation (light and heat) and on climate. At each of the ARM sites is a collection of instrumentation that makes continuous and largely automated measurements of all sorts (see this link for more information). All ARM data is freely and publicly available for download by researchers and anyone else here. This is exactly the approach needed to study such a complex topic as climate and global warming.
The primary work that Larry has done with ARM involves analyzing measurements from balloon-borne instruments called radiosondes in order to improve the accuracy of the temperature and humidity measurements that they make. The results of his work are used not only to make better instruments that take more accurate readings in the future, but also to go back and correct historical readings. His research ultimately benefits weather forecasts and computer climate simulations. This is how he describes his research:
Radiosonde measurements (like all measurements) have sources of error, such as imperfect calibration accuracy from the manufacturer, and solar heating of the sensor during the daytime, and slow sensor response at low temperatures, among other things. My method of deriving a correction is to compare radiosonde measurements to measurements from other more accurate instruments, and to do computer modeling of how the sensor responds to changing conditions based on laboratory experiments. Then I write up my method and results and submit a paper to a technical journal, and the editor sends it out for “peer review” where others who are knowledgeable about this area of study scrutinize the paper in great detail and submit line-by-line comments and a recommendation about publishing it. Then I must respond to the editor’s satisfaction about each of the reviewer comments and explain either how I changed the paper to address the comment or why I thought it better not to change it. If the paper is published, it has been “vetted” by experts, and other scientists will use the ideas to make their data better, and someone else will come along one day with a better idea that gives better results and science will again move incrementally forward. If the paper doesn’t pass muster with the reviewers and editor, then the idea probably won’t gain much attention. That’s how science works.
I’ve had the opportunity to watch Larry build new instruments and learned about the various aspects of design he considers. This gives me both insight into the challenges as well as faith in the science.
While I understand the basics of how contrails form from the exhaust of jet engines, Larry again describes this much better than I do, so I’m going to quote him as a preface to explaining why I think that what are called chemtrails are actually normal jet contrails and probably not of serious concern:
Jet engines emit heat, water vapor and combustion products like soot and sulfate aerosols into the atmosphere, which immediately forms a contrail when the exhaust begins to mix with the atmosphere and cool. Cooling causes the air to become supersaturated and form droplets by condensation on the aerosols, somewhat like the way a glass of ice water will cause condensation of water vapor on the outside, because the thin layer of air next to the glass is cool and the air can't hold as much water vapor at lower temperatures (relative humidity exceeds 100%) so the "excess" water vapor condenses on the glass. What happens to the contrail depends on the atmospheric temperature and relative humidity, and on how much heat/moisture/aerosols are injected (which depends on the fuel type and the engine efficiency). If the atmosphere is very dry then the mixing of exhaust and atmosphere will quickly drop the mixture below 100% relative humidity with respect to ice ("ice-saturation") and the contrail will evaporate in seconds. If the atmosphere is closer to ice-saturation then the contrail will last longer because more mixing is needed to dilute the contrail enough that the relative humidity drops below ice-saturation and the contrail evaporates. If the atmosphere is already at or above ice-saturation, then no amount of mixing will bring the contrail below ice-saturation, it will simply spread and in fact it can grow since the atmosphere was already primed for cloud formation (supersaturated air). These are termed "persistent contrails" and they can evolve into what's called "contrail cirrus".
I like to think that I’m an open-minded skeptic. It is possible that one of the chemtrail conspiracies is true and that we really are being poisoned, deliberately or not, despite what my friend tells me. I certainly can't claim to know beyond doubt that chemtrails are false and I will always be open to new evidence (which I’ll still treat with the skepticism that such extraordinary claims require). As I've explored the current evidence I've tended toward greater and greater doubts about these theories. I do, however, have serious fears about proposed geo-engineering approaches to fixing climate change and I believe that skepticism about such future plans is definitely warranted.
Knowing the difficulties of proving a negative (that chemtrails don’t exist), I tried a few different approaches to help ease the mind of my friend who fears for her children:
1) If the government's objective is to poison us, why bother with the expense, complication and uncertainty of airborne dispersal? Why not put the chemicals directly into the water supply? Surely that would be a much more effective and discreet method of poisoning the populace.
2) Wouldn't the pilots, mechanics and scientists involved fear for the safety of their own families and object? Wouldn't the instigators of such a conspiracy be equally vulnerable to the effects of the toxic chemicals and viruses?
3) A program designed to blanket the entire country (or entire world, as some believe) would require thousands of planes and the collaboration of tens of thousands of people supporting this mission. The scope of the program works against the need to keep it secret and the chance of someone defecting from the conspiracy is high.
Regardless of one’s opinion of Wikileaks, there’s an interesting point made by Julian Assange that is worth consideration here: conspiracies inevitably create resistance and so they must cloak their doings in secrecy and compartmentalize the knowledge of conspirators from each other. The need for secrecy and partitioning in turn inhibits and limits the total operating capability of the conspiracy. The bigger a conspiracy gets, the more likely it will be exposed.
There are rebuttals to all of my logical objections that invoke further conspiracies. Once you start down the rabbit hole, it just gets darker. For readers who are interested in going there, see David Icke who believes this is part of a conspiracy by a race of alien reptilians running our world.
I don't believe in reptilian overlords, but I do believe in the model of the triune brain and its reptilian complex which is the seat of our most primitive survival instincts for food, sex and safety. The “fight or flight” response belongs to the lizard brain that is much better adapted for life on the savanna where the biggest threats are lions. Today we live in a world where information about possible threats has proliferated to a degree that is overwhelming our poor lizard brains. I grew up during the Cold War when the world was a little simpler in some ways and the “red menace” served as a kind of focal point for our fears. The 1950s and 1960s version of the chemtrail conspiracy was fluoridation as a Soviet mind-control plot and to this day some people still claim there is a fluoride conspiracy.
Now we hear about new carcinogens all the time and there's a myriad other threats facing us and our loved ones: gang violence, global warming, peak oil, peak water, honeybee and bat die-offs, overpopulation, overfishing, inflation, deflation, deforestation, ocean acidification, and gender-bending endocrine disruptors to name just a few. The news is bad, really really bad. And I think at a certain point some people become so overwhelmed that they would rather have some big conspiracy like chemtrails that ties together many disparate fears into one relatively neater package. It creates a monolithic enemy that will be the main focus of all one's wariness and defensive energies. It’s easier on the mind to worry about one big conspiracy than a hundred different nebulous threats always looming on the horizon.
I believe that some conspiracies do exist and I don't trust governments or corporations to always (or even usually) do what’s in our best interests. The Iran-Contra Affair was one of the biggest conspiracies to be revealed in my lifetime, right behind COINTELPRO. I think the long-term tendency is for the real conspiracies to eventually come to light. I think Julian Assange is correct that conspiracies are limited in size and power by their need to be secret. In the long haul, I believe that the truth will inevitably come out.
Since everyone else has one, I've developed my own conspiracy theory to explain chemtrails. I think the conspiracies themselves are the product of a few fanatics who want to demonize science because it threatens their world view. There also seems to be an attempt to smear climate scientists in particular in most of these theories and I think that benefits the energy companies who are threatened by climate change legislation. The wide variety of possible explanations for chemtrails may be deliberate so as to create this thought: if so many people are researching chemtrails from so many different angles, there must be something to it!
Personally I have little doubt that humans are responsible for the increase in CO2 and that is raising global temperatures. You don't need chemtrail conspiracies to realize that airplanes are already spewing poisons into the air. Jet fuel is made of toxic petrochemicals, and those contrails do inevitably (and inadvertently) have some particulate pollution in them. No one denies this. In a twisted way, the chemtrail claim is actually true and has been true for as long as we've been flying.
We're consuming on the order of 100 million barrels of oil globally every day. That's a very obvious source of poison that is making us sick. We're also burning a commensurate amount of coal and natural gas, not to mention wood and dung in less developed countries. It takes a lot of fuel to keep 6+ billion people warm and happy. If we didn't have tailpipes, smokestacks and chimneys because the emissions were constantly re-captured, the climate change problem wouldn’t be as pressing. The sheer volume of fuel being extracted and burned is so great that it would be amazing to me if it wasn't having an effect on climate. If you’re interested in learning more about the science of global warming from a research scientist, then have a look at Larry’s article Global Warming in a Nutshell.
These scans show what contrails looked like in 1972. A wide variety of formations can be seen. While the pictures don't demonstrate how long the contrails persisted, back then it was known that their longevity varied based on the local conditions and it wasn't unusual for contrails to last for hours. Most conspiracy theorists hold that the contrails started changing in the late 1990s. I imagine that this was a time when the conspiracies started to circulate more widely because the Internet was gaining popularity. People who'd never sat and watched a contrail for an hour started doing it, and because they’d never paid much attention to it before the effect seemed unnatural. There are also more contrails than ever before simply because there are more jets than ever before. Further, it is quite possible that some contrails are persisting longer and dispersing differently as a result of the climate change caused by increasing CO2 emissions.
Since 1994 I have periodically watched contrails over the course of hours while camping out in the Utah desert with Larry. It's been a great education for me, though I'm still relatively ignorant about the science behind it. I definitely have my own personal beliefs and biases about how I think that the world works. It is possible that the global warming I believe in is really nothing but a conspiracy and that the lizard people are really culling the human herd with chemtrails. I don't think it's likely, but it's at least possible.
The thing is, I trust science to get it right in the long haul. Most scientists are very dedicated to the cause of learning and discovery and are innately curious as human beings. They want to contribute something of value to the body of human knowledge. My faith in science isn't blind. It's based on a history of proven results. It’s also grounded in an understanding of how the scientific method works and how peer review catches mistakes. Science is less prone to orthodoxy than most other human ways of knowing the world. This is because there are so many rewards to overthrowing conventional knowledge. Any discovery that isn't based on empirical facts is naturally subject to being overthrown the quickest when people attempt to replicate an experiment. This makes science a marvelous self-correcting system where the rewards for cheating or lying are usually just too small in relation to the risks. That isn’t to say there is never fraud or cheating or just plain stupidity. Individual scientists are always fallible and rightly subject to questioning. My faith goes to the whole scientific endeavor to find and correct those failings over time.
So if chemtrails are a real wide-spread phenomena, I’m pretty certain that the dedicated scientists who are studying the atmosphere and love truth for the sake of truth will catch on. There will always be isolated scientists who fall for any given conspiracy theory and claim it is the truth because they personally studied it. When their results are published in the journals and other scientists replicate those results, I’ll pay a lot more attention. Until then, the chemtrail conspiracy is low on my list of threats to humanity.
[Broken External Image]:https://lh4.googleusercontent.com/O...SpgzUgjELqfK22-XMH6h0dNA6Pwuve-wiT-yLBaywJ1OU
This is a photo from a trip to the San Rafael Desert in the spring of 2002. The original can be viewed here. To double-check my own amateur knowledge I wrote Larry and asked him if he thought this was a good example of contrail cirrus. This is what he wrote back:
Yes it does look like contrail cirrus. For sure the linear features with ice crystals falling out. Others that are more isolated puffs may be "cirrus uncinus", which form the way cirrus normally do, by the air being cooled by one or another mechanism until the humidity reaches the "homogeneous nucleation threshold", which is approximately 150% relative humidity with respect to ice. Substantial supersaturation is needed for cirrus to form this way, as opposed to "heterogeneous nucleation" where ice crystals form directly on some solid aerosol particle at lower supersaturations.
Here's hoping the copy/paste from Google Docs preserved all the links intact...
Chemtrails: Lizard Overlords or Lizard Brain Overload?A conspiracy theory case study
The word chemtrail is short for "chemical contrails" and refers to a conspiracy theory that some combination of chemical and biological agents is being deliberately sprayed from airplanes, usually over populated areas. I first learned about this threat last summer when a friend told me about her deep fears for her children’s health. She explained that chemtrails could be any number of things, including a secret U.N. plot involving mind control or possibly even population control.
I did a little research and learned more about a wide variety of chemtrail conspiracies that are only loosely related to each other. Google has indexed more than 1.5 million pages that mention the word. One popular version of the conspiracy theory holds that they are part of so-called geo-engineering experiments designed to reverse global warming. Another version claims that chemtrails are designed to create an electromagnetic shield that protects our electronics from disruptions. Over at chemtrailagenda.com I learned that I'm living in the brave new world of toxic barium skies, weather control, mind control and population control through the use of chemtrails modulated with electromagnetic frequencies generated by HAARP. NaturalNews.com recently published Chemtrails are now a deadly fact (strangely their headline is also labeled ‘opinion’ in parentheses). From that article I learned that the government program to blame for chemtrails is called Atmospheric Radiation Measurement (ARM). NaturalNews.com helpfully offers to sell me an herbal remedy to keep me safe from the effects of chemtrails.
My friend Larry is a scientist who has worked with ARM periodically over the years and he describes their mission and methods better than I can:
ARM is a DOE facility with the mission to conduct measurements and support research into better understanding the effects of clouds and aerosols on radiation (light and heat) and on climate. At each of the ARM sites is a collection of instrumentation that makes continuous and largely automated measurements of all sorts (see this link for more information). All ARM data is freely and publicly available for download by researchers and anyone else here. This is exactly the approach needed to study such a complex topic as climate and global warming.
The primary work that Larry has done with ARM involves analyzing measurements from balloon-borne instruments called radiosondes in order to improve the accuracy of the temperature and humidity measurements that they make. The results of his work are used not only to make better instruments that take more accurate readings in the future, but also to go back and correct historical readings. His research ultimately benefits weather forecasts and computer climate simulations. This is how he describes his research:
Radiosonde measurements (like all measurements) have sources of error, such as imperfect calibration accuracy from the manufacturer, and solar heating of the sensor during the daytime, and slow sensor response at low temperatures, among other things. My method of deriving a correction is to compare radiosonde measurements to measurements from other more accurate instruments, and to do computer modeling of how the sensor responds to changing conditions based on laboratory experiments. Then I write up my method and results and submit a paper to a technical journal, and the editor sends it out for “peer review” where others who are knowledgeable about this area of study scrutinize the paper in great detail and submit line-by-line comments and a recommendation about publishing it. Then I must respond to the editor’s satisfaction about each of the reviewer comments and explain either how I changed the paper to address the comment or why I thought it better not to change it. If the paper is published, it has been “vetted” by experts, and other scientists will use the ideas to make their data better, and someone else will come along one day with a better idea that gives better results and science will again move incrementally forward. If the paper doesn’t pass muster with the reviewers and editor, then the idea probably won’t gain much attention. That’s how science works.
I’ve had the opportunity to watch Larry build new instruments and learned about the various aspects of design he considers. This gives me both insight into the challenges as well as faith in the science.
While I understand the basics of how contrails form from the exhaust of jet engines, Larry again describes this much better than I do, so I’m going to quote him as a preface to explaining why I think that what are called chemtrails are actually normal jet contrails and probably not of serious concern:
Jet engines emit heat, water vapor and combustion products like soot and sulfate aerosols into the atmosphere, which immediately forms a contrail when the exhaust begins to mix with the atmosphere and cool. Cooling causes the air to become supersaturated and form droplets by condensation on the aerosols, somewhat like the way a glass of ice water will cause condensation of water vapor on the outside, because the thin layer of air next to the glass is cool and the air can't hold as much water vapor at lower temperatures (relative humidity exceeds 100%) so the "excess" water vapor condenses on the glass. What happens to the contrail depends on the atmospheric temperature and relative humidity, and on how much heat/moisture/aerosols are injected (which depends on the fuel type and the engine efficiency). If the atmosphere is very dry then the mixing of exhaust and atmosphere will quickly drop the mixture below 100% relative humidity with respect to ice ("ice-saturation") and the contrail will evaporate in seconds. If the atmosphere is closer to ice-saturation then the contrail will last longer because more mixing is needed to dilute the contrail enough that the relative humidity drops below ice-saturation and the contrail evaporates. If the atmosphere is already at or above ice-saturation, then no amount of mixing will bring the contrail below ice-saturation, it will simply spread and in fact it can grow since the atmosphere was already primed for cloud formation (supersaturated air). These are termed "persistent contrails" and they can evolve into what's called "contrail cirrus".
I like to think that I’m an open-minded skeptic. It is possible that one of the chemtrail conspiracies is true and that we really are being poisoned, deliberately or not, despite what my friend tells me. I certainly can't claim to know beyond doubt that chemtrails are false and I will always be open to new evidence (which I’ll still treat with the skepticism that such extraordinary claims require). As I've explored the current evidence I've tended toward greater and greater doubts about these theories. I do, however, have serious fears about proposed geo-engineering approaches to fixing climate change and I believe that skepticism about such future plans is definitely warranted.
Knowing the difficulties of proving a negative (that chemtrails don’t exist), I tried a few different approaches to help ease the mind of my friend who fears for her children:
1) If the government's objective is to poison us, why bother with the expense, complication and uncertainty of airborne dispersal? Why not put the chemicals directly into the water supply? Surely that would be a much more effective and discreet method of poisoning the populace.
2) Wouldn't the pilots, mechanics and scientists involved fear for the safety of their own families and object? Wouldn't the instigators of such a conspiracy be equally vulnerable to the effects of the toxic chemicals and viruses?
3) A program designed to blanket the entire country (or entire world, as some believe) would require thousands of planes and the collaboration of tens of thousands of people supporting this mission. The scope of the program works against the need to keep it secret and the chance of someone defecting from the conspiracy is high.
Regardless of one’s opinion of Wikileaks, there’s an interesting point made by Julian Assange that is worth consideration here: conspiracies inevitably create resistance and so they must cloak their doings in secrecy and compartmentalize the knowledge of conspirators from each other. The need for secrecy and partitioning in turn inhibits and limits the total operating capability of the conspiracy. The bigger a conspiracy gets, the more likely it will be exposed.
There are rebuttals to all of my logical objections that invoke further conspiracies. Once you start down the rabbit hole, it just gets darker. For readers who are interested in going there, see David Icke who believes this is part of a conspiracy by a race of alien reptilians running our world.
I don't believe in reptilian overlords, but I do believe in the model of the triune brain and its reptilian complex which is the seat of our most primitive survival instincts for food, sex and safety. The “fight or flight” response belongs to the lizard brain that is much better adapted for life on the savanna where the biggest threats are lions. Today we live in a world where information about possible threats has proliferated to a degree that is overwhelming our poor lizard brains. I grew up during the Cold War when the world was a little simpler in some ways and the “red menace” served as a kind of focal point for our fears. The 1950s and 1960s version of the chemtrail conspiracy was fluoridation as a Soviet mind-control plot and to this day some people still claim there is a fluoride conspiracy.
Now we hear about new carcinogens all the time and there's a myriad other threats facing us and our loved ones: gang violence, global warming, peak oil, peak water, honeybee and bat die-offs, overpopulation, overfishing, inflation, deflation, deforestation, ocean acidification, and gender-bending endocrine disruptors to name just a few. The news is bad, really really bad. And I think at a certain point some people become so overwhelmed that they would rather have some big conspiracy like chemtrails that ties together many disparate fears into one relatively neater package. It creates a monolithic enemy that will be the main focus of all one's wariness and defensive energies. It’s easier on the mind to worry about one big conspiracy than a hundred different nebulous threats always looming on the horizon.
I believe that some conspiracies do exist and I don't trust governments or corporations to always (or even usually) do what’s in our best interests. The Iran-Contra Affair was one of the biggest conspiracies to be revealed in my lifetime, right behind COINTELPRO. I think the long-term tendency is for the real conspiracies to eventually come to light. I think Julian Assange is correct that conspiracies are limited in size and power by their need to be secret. In the long haul, I believe that the truth will inevitably come out.
Since everyone else has one, I've developed my own conspiracy theory to explain chemtrails. I think the conspiracies themselves are the product of a few fanatics who want to demonize science because it threatens their world view. There also seems to be an attempt to smear climate scientists in particular in most of these theories and I think that benefits the energy companies who are threatened by climate change legislation. The wide variety of possible explanations for chemtrails may be deliberate so as to create this thought: if so many people are researching chemtrails from so many different angles, there must be something to it!
Personally I have little doubt that humans are responsible for the increase in CO2 and that is raising global temperatures. You don't need chemtrail conspiracies to realize that airplanes are already spewing poisons into the air. Jet fuel is made of toxic petrochemicals, and those contrails do inevitably (and inadvertently) have some particulate pollution in them. No one denies this. In a twisted way, the chemtrail claim is actually true and has been true for as long as we've been flying.
We're consuming on the order of 100 million barrels of oil globally every day. That's a very obvious source of poison that is making us sick. We're also burning a commensurate amount of coal and natural gas, not to mention wood and dung in less developed countries. It takes a lot of fuel to keep 6+ billion people warm and happy. If we didn't have tailpipes, smokestacks and chimneys because the emissions were constantly re-captured, the climate change problem wouldn’t be as pressing. The sheer volume of fuel being extracted and burned is so great that it would be amazing to me if it wasn't having an effect on climate. If you’re interested in learning more about the science of global warming from a research scientist, then have a look at Larry’s article Global Warming in a Nutshell.
These scans show what contrails looked like in 1972. A wide variety of formations can be seen. While the pictures don't demonstrate how long the contrails persisted, back then it was known that their longevity varied based on the local conditions and it wasn't unusual for contrails to last for hours. Most conspiracy theorists hold that the contrails started changing in the late 1990s. I imagine that this was a time when the conspiracies started to circulate more widely because the Internet was gaining popularity. People who'd never sat and watched a contrail for an hour started doing it, and because they’d never paid much attention to it before the effect seemed unnatural. There are also more contrails than ever before simply because there are more jets than ever before. Further, it is quite possible that some contrails are persisting longer and dispersing differently as a result of the climate change caused by increasing CO2 emissions.
Since 1994 I have periodically watched contrails over the course of hours while camping out in the Utah desert with Larry. It's been a great education for me, though I'm still relatively ignorant about the science behind it. I definitely have my own personal beliefs and biases about how I think that the world works. It is possible that the global warming I believe in is really nothing but a conspiracy and that the lizard people are really culling the human herd with chemtrails. I don't think it's likely, but it's at least possible.
The thing is, I trust science to get it right in the long haul. Most scientists are very dedicated to the cause of learning and discovery and are innately curious as human beings. They want to contribute something of value to the body of human knowledge. My faith in science isn't blind. It's based on a history of proven results. It’s also grounded in an understanding of how the scientific method works and how peer review catches mistakes. Science is less prone to orthodoxy than most other human ways of knowing the world. This is because there are so many rewards to overthrowing conventional knowledge. Any discovery that isn't based on empirical facts is naturally subject to being overthrown the quickest when people attempt to replicate an experiment. This makes science a marvelous self-correcting system where the rewards for cheating or lying are usually just too small in relation to the risks. That isn’t to say there is never fraud or cheating or just plain stupidity. Individual scientists are always fallible and rightly subject to questioning. My faith goes to the whole scientific endeavor to find and correct those failings over time.
So if chemtrails are a real wide-spread phenomena, I’m pretty certain that the dedicated scientists who are studying the atmosphere and love truth for the sake of truth will catch on. There will always be isolated scientists who fall for any given conspiracy theory and claim it is the truth because they personally studied it. When their results are published in the journals and other scientists replicate those results, I’ll pay a lot more attention. Until then, the chemtrail conspiracy is low on my list of threats to humanity.
[Broken External Image]:https://lh4.googleusercontent.com/O...SpgzUgjELqfK22-XMH6h0dNA6Pwuve-wiT-yLBaywJ1OU
This is a photo from a trip to the San Rafael Desert in the spring of 2002. The original can be viewed here. To double-check my own amateur knowledge I wrote Larry and asked him if he thought this was a good example of contrail cirrus. This is what he wrote back:
Yes it does look like contrail cirrus. For sure the linear features with ice crystals falling out. Others that are more isolated puffs may be "cirrus uncinus", which form the way cirrus normally do, by the air being cooled by one or another mechanism until the humidity reaches the "homogeneous nucleation threshold", which is approximately 150% relative humidity with respect to ice. Substantial supersaturation is needed for cirrus to form this way, as opposed to "heterogeneous nucleation" where ice crystals form directly on some solid aerosol particle at lower supersaturations.
