Global warming is a concern, and many have come to believe it is a reality. But, has it been going on for over a century? One warning sign that was misunderstood for years may well indicate global warming. Perhaps there is a connection between global warming and noctilucent clouds. At least NASA has suggested the possibility on one of its web pages. This is something that is difficult to study, so speculation and best scientific guesses are what we need to consider.
Global Warming: Warning from the Sky
Global warming is a serious problem, and it is quite possible that nature was sounding the alarm for over a century. Do noctilucent clouds herald a warming Earth?
What Are Noctilucent Clouds?
Noctilucent clouds, also called NCLs, are very thin ice clouds in the upper atmosphere. Most of our weather occurs in the troposphere, above that is the stratosphere, then comes the mesosphere, and it is in the mesosphere that we find noctilucent clouds. They are miles above the weather. They are so high that they are illuminated long after the sun sets, hence the name. They reflect sunlight in a dark sky. While they are quite beautiful wisps of ice shining after sunset with a bluish-white color, they may herald an increasing warmer Earth.
One question that plagued scientists for a long time was where does the ice come from? Well, comets often have a significant ice component, so debris from comes from them could allow ice to enter the Earth’s atmosphere from above. It has also been suggested that warmer temperatures could buoy water vapor higher in the atmosphere. I personally favor the ice from above idea.
Another is what can the ice condense on? Clouds form best when there are condensation nuclei. Well, small bits of metal and dust remain after meteors streak through the sky. Yes, hey vaporize, but small bits of material from old meteors remain, and solidify from the melted material. Electrons from the sun also enter the upper atmosphere and charge up these small particles. Charged particles are excellent condensation nuclei. So, the water vapor has a place to condense.
The Old Theory
Since the first mention of noctilucent clouds having been observed occurred shortly after the eruption of Krakatoa, it was initially thought Krakatoa ejected both dust and water vapor into the mesosphere, and the clouds condensed. Krakatoa was a particularly violent explosion, and the explosion was directed upward, the two requirements for sending material up to about eighty thousand feet. Later volcanic eruptions were less violent, or as is the case with Mount Saint Helens directed sideways.
The problem with the old theory was dust should settle out, yet noctilucent clouds not only persisted but were increasing in coverage. This brought about a serious question of how significant are volcanoes in noctilucent cloud formation? Apparently, the obvious apparent conclusion was flawed.
The fact is these clouds occur far from the equator. Yet they are being observed closer to the equator over time. This indicates the mesosphere is cooling. NASA has suggested the greenhouse gases may be responsible. Hence, a warming troposphere is consistent with a cooling of the mesosphere, and ice forms better as the temperature decreases.
Krakatoa may have been coincidental to the Earth having reached a tipping point with the industrial revolution being the culprit. Pollution is not new, it is just reaching a point of serious concern and greater awareness. And perhaps the sky is giving us a fair warning.