June 2021 – Burst of Insights

Humans have been curious about the nature of the atmosphere for thousands of years. However, the effect of this enduring curiosity started to bear meaningful fruit only within the last four hundred years. This mixture of gases that sustained life for billions of years had been elusive to our ancestors. They, of course, did not doubt its existence. The transparency of it did not shadow the chilling breezes, the hurricanes, the tornadoes, the lightings, and the storms it caused. In fact, they moved with it – crossing oceans, seas and straits using boats fueled by winds – and diversified.

For our ancestors, the atmosphere was not just mysterious substances that enveloped the Earth as a blanket. It was rather a magical force of life without which they could not survive, and its god, at least for the Greeks, is none other than Zeus himself, the personification of justice that speaks to thunders and storms. Different civilizations had ways of attributing the undeniable power of the atmosphere to similar mythical gods.

This is an interesting conceptualization, but one that made our ancestors more of stoics and passive and the atmosphere esoteric and unexplorable. Exploring the atmosphere was more like counting the infinite numbers between any two successive Natural numbers, or more like being physically symbiotically cell-close with something that is infinitely foreign to the mind. This recalls what David Wallace Foster once said:

There are these two young fish swimming along, and they happen to meet an older fish swimming the other way, who nods at them and says, “Morning, boys. How’s the water?” And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes, “What the hell is water?”

Like the young fish in the water, we had been to a certain extent passive to the atmosphere, unable to see it as a mixture of gases that in many ways gave rise to and sustained life. Like the older fish, we needed the same kind of sage, some insightful observers to enlighten us about the air we breathe. Like the older fish that made peace with the water it swims in, the giants among us had to decide and begin at the beginning to study the atmosphere with deceptively simple yet clever methods.

In 1648, Blaise Pascal and Florin Perier collected atmospheric pressure data from Puy-de-Dome using a barometer which was invented by Evangelista Toricelli. Their finding suggests that atmospheric pressure decreases with increasing elevation. Roughly after 139 years, Horace Benedict de Saussure, who was an Earth Scientist by profession, indicated that both atmospheric pressure and temperature decrease with increasing altitude. He collected his data by climbing up to the summit of Mount Blanc. Saussure suffered from altitude sickness and had shortened his expedition as a result.

This continued dream of advancing the frontier of atmospheric science inspired a dangerous and elaborated balloon flight by Henry Coxwell and James Glaisher in 1862. Records show that this might have been the first scientific expedition to make it into the Stratosphere, whose boundary was later identified by Teisserenc de Bort and Richard Assmann in 1902.

In just about 254 years, these great scientists were able to gain important knowledge about the atmosphere that eluded our ancestors for thousands of years. The seed of this major scientific transformation appears to be not taking things for granted, and its continued germination has been supported by the efforts of bright scientists who developed insightful and clever methods to critically examine and discover the remarkable nature of the world around us.

After thousands of years of philosophical speculations and religious assertions, one of the major experimental breakthroughs in atmospheric science was conducted by Joseph Black who released carbon dioxide by burning limestone (calcium carbonate) in 1750. Most importantly, Black was able to reverse engineer this reaction to precipitate out calcium carbonate by bubbling carbon dioxide through a calcium hydroxide solution. This experiment helped him to show that carbon dioxide is present in animal breath, and hence in the atmosphere. Interestingly, he was also able to combine calcium oxide with atmospheric carbon dioxide to form limestone. The original name given to this gas by Black was ‘Fixed air’. Incidentally, calcium hydroxide is formed when calcium oxide (rock formed when limestone is burned at a temperature of 960 °C or higher) mixes with water. This technology was known since ~7000 BCE to ancient civilizations such as the Anatolian civilization, now Turkey.

Following the discovery of carbon dioxide, in 1766, the great experimental scientist Henry Cavendish was able to release the hydrogen gas by combining metal (e.g., zinc) with hydrochloric acid. At the time, he thought that the hydrogen gas was phlogiston – a substance which was mistakenly thought to have been released when burning a combustible body.

In 1774, Joseph Priestly conducted an experiment and released what he called a dephlogisticated gas. This experiment was also conducted by Antoine Lavoisier who first obtained calx of mercury, which at that time was referred to as the ash that is formed when a substance is burned in the air. Antoine Lavoisier was able to obtain calx of mercury by burning mercury in air at moderate temperatures. The most exciting and transformative part of his experiment is however the decomposition of the calx of mercury into their respective mercury and oxygen parts. This remarkable achievement, which was also specified by Joseph Priestly, changed the history of chemistry, and overall, the discourse of Earth Sciences forever. Equally transformative discoveries of gases include the identification of nitrogen by Henry Rutherford in 1772 and the identification of noble gases by William Ramsey (1894 – 1889).

Remarkable progress has been made in atmosphere science after the elements that make up the atmosphere are identified. Thanks to the giants who devoted themselves for this worthy cause, now advances in Earth Sciences are moving with a staggering pace. The future is being realized now.

Atmospheric pressure and temperature measurements that were initially made by climbing mountains just within the lower limits of the troposphere, are now being made through the entire column of the troposphere, the stratosphere, the Mesosphere, and the Thermosphere using hi-tech balloons, aircrafts, and satellites, measuring the physical and compositional variations of over a 1000 km thick vertical column of air.

However, there is still much to be done to understand the origin and the evolution of the atmosphere and its interactions with the biosphere, the geosphere, and the cryosphere. This might indeed appear as a daunting task. However, as the history of atmospheric science clearly shows, extremely consequential observations maybe made by beginning at the beginning and by asking the right questions.

© Authored by Luel Emishaw, Burst of Insights

The Atmosphere Paul I Palmer

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