Richard Cronin

Just got to thinking about the folly of even declaring a "global temperature” and the assumptions of a homogeneous terrestrial system for heat distribution tied to radiation.

Anyone who has sailed on the open ocean will observe that on a relatively balmy day the bottoms of the clouds are invariably as flat as a pancake. The clouds sit at a uniform height above the flat ocean surface. But as warm, moist ocean air moves over land the air mass flows up over coastal plains and uplands. It gains elevation to start condensing and forming the aerosol droplets of clouds. Clouds shade the land and provide reflective albedo, cooling things off. Then precipitation.

Now then, 2/3rds of the continental land mass is in the Northern Hemisphere. We witness how the Japan Current delivers moist air, clouds and precipitation from the Aleutian Islands down to the rainy Pacific Northwest. The North Atlantic Gulf Stream delivers clouds and precipitation across Iceland, Norway, Ireland, the UK, all the way down to the Iberian peninsula.

In the Southern Hemisphere we have the clouds and rains across the Argentinian pampas and Tierra del Fuego but the interiors of Australia and South Africa are quite arid and cloudless.

Overcast conditions dominate in the Northern Hemisphere.

This relates to solar activity and Forbush Reductions wherein solar proton events diminish cloud cover. The Solar Cycle runs every 11 years. Notable exceptions were the Maunder Minimum (1645 - 1715) and Dalton Minimum.

The Dalton Minimum spanned 1790 to 1830. It was overcast, with invariable gloom and damp.

In 1850, John Tyndall gazed out on a sunny day in the Alps and worried that his favorite glaciers seemed to be retreating. Of course, in sunlight and dry, elevated low pressure conditions of the mountains there is sublimation. Water vapor produced directly from ice.

Nope. The first thought that sprang to Tyndall’s mind: "Man did this by burning coal.”

Wait !! There’s more !!

The Maunder Minimum provided sustained overcast conditions. Damp and gloomy conditions produced several poor harvests in the late 1600s. In 1692 a fungus developed on rye crops in New England. It caused allergic and hallucinogenic reactions in the farm girls.

The Salem Witch trials ensued.

We haven’t progressed so very much further in understanding gloomy weather.

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