By Jim Steele
With a disproportionate focus on the greenhouse effect and fossil fuels, most people are totally unaware that the earth’s surface is cooled primarily by convection currents carrying warm buoyant air up and away. Indeed, with water vapor and CO2 making the lower 1000 meters of the atmosphere opaque to most escaping infrared, thus preventing radiative cooling, the earth’s surface only cools sufficiently via convection. All honest scientists know heatwaves are caused by suppressed convection.
Graphic A shows a typical heat dome resulting from a high-pressure system that causes sinking air that suppresses rising convection. Air sinking from the colder upper atmosphere is dry and thus maintains clear skies that increase solar heating. A warmer earth surface from climate change should cause rising air, so what causes sinking air?
In the tropics, the greatest warming happens around the equator and that draws in air from the northern and southern hemisphere. Where that surface air converges (aka Intertropical Convergence Zone) air is forced upwards. What goes up must come down, and to maintain balance the air sinks around 30 degrees north and south, forming high pressure systems over the desert latitudes (Hadley Circulation). Outside the tropics the main driver of high-pressure systems is the convergence of upper atmosphere winds in wavy jet streams.
As a kid we loved to play “crack the whip” when skating. A line of 4 or more kids had a single kid on one end stop, which caused the moving line to make an arc. The kid on the other end naturally speeds up to cover the arc’s bigger circumference and thus “whips” around. Likewise, the ridge of a wavy jet stream in the upper atmosphere causes air flow to speed up. When the air flow enters a trough, the air flow slows down. The fast-moving air mass then collides with the slow-moving air causing an upper air convergence that forces air downward generating a high-pressure system (graphics B & C). Similarly, anyplace where upper air currents converge will cause a high-pressure system. How intensive the resulting heat wave depends on how fast the high-pressure system moves eastward.
In the upper atmosphere, the winds of the jet stream average 80–140 miles per hour eastward. That steers the pressure systems of the lower atmosphere. Friction with earth’s surface reduces the speed of a pressure systems to about half the speed of the jet stream. As the jet stream moves over or around mountains, or moves between water and land, or cold air interacts with warm air, or interacts with other pressure systems, the jet stream may be forced to loop more north and south. That reduces the eastward steering speed of the jet stream which causes surface high-pressure systems to slow down or stall. In that case, a lingering high-pressure system will cause an intensifying heat wave.
The wavier jet stream over the northeast Pacific Ocean commonly generates a “blocking high” in that region (graphic D). That blocking high caused Canada’s record high temperatures during a heatwave that stalled over Lytton, British Columbia June 29, 2021. The wavier jet stream also causes frequent blocking highs over Greenland, which caused excessive melting during July 2021. Meteorologist studying heat waves have mapped out regions where blocking highs are most likely to form (graphic E). Combined with monitoring of the jet stream and interacting pressure systems, meteorologist can predict when and where a heat wave is likely to form.
Any warming of the earth’s surface from the greenhouse effect or any other cause, would cause air to rise, the exact opposite of how heat waves are formed. To blame heat waves on rising CO2, alarmists must use statistical attribution tricks. They simply claim higher global average temperatures make the heat wave hotter, even when the heat wave is centered over regions where the has been no local warming. Clearly there are lies, damn lies and statistics and most alarmist climate scientists know how to manipulate statistics.
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