by: Dr Tim Ball
Finally, a weather person has mentioned the word “blocking” when talking about the heat and fires in Moscow. It’s a natural event as the world shifts from the warming trend of the 1990s to a cooling trend since 2000. Distortion of reality about global temperatures continues with warming claims while Western North America, most of Eurasia and large areas of the southern hemisphere report below normal temperatures. It’s been the coldest summer on record north of 80°N latitude and rate of sea ice melt continues to decrease.
Recently the Peruvian government declared a state of emergency as hundreds of people died from the coldest temperatures in 50 years.
Fifty years ago there was a cooling trend as global temperatures declined from 1940 to 1980. It troubled promoters of human CO2 as the cause of global warming. During the cooling period, CO2 from human activity increased the most in human history. They tried to solve the problem by plugging variables into the models until results equaled what was happening. It has nothing to do with reality, but allows them to claim their models work because they recreate past conditions. It’s even better if the cause has a human source. In the 1940–80 cooling, they added sulfates. Trouble is sulfate additions continued but global temperatures began to rise.
Obsession with finding human causes means they ignore what we know about natural mechanisms. Failure to include natural mechanisms is complicated by lack of knowledge or understanding of weather and climate mechanisms by most involved in the politics of climate science.
Upper Level Winds: The Jet Stream
Pilots flying pressured bombers from Pacific islands in WWII were surprised to find strong high level winds. They’d discovered the Jet Stream, a massive river of wind that is part of the circulation known as the Circumpolar Vortex. Figure 1 shows the Jet Stream in three-dimension so its relationship to the Polar Front that separates warm and cold air is visible.
A major feature of the cold atmospheric circulation is the strong wind pattern in both hemispheres known as the Circumpolar Vortex. It is created by the temperature difference across the Polar Front that separates cold polar air and warm tropical air.
Figure 1: Three dimensional image of the location of the Jet Stream relative to the dome of cold polar air and the Polar Front. Source: Briggs, Smithson and Ball et al.
Usually called the Jet Stream, technically that applies only to narrow tubes of high-speed winds within the Vortex. Figure 2 is another depiction of the vortex showing different wave patterns on a pressure map. In 1946, Carl Gustav Rossby identified the major waves in the Vortex now called Rossby Waves; some call them Planetary Waves. They interact with major north/south mountain chains such as the Rockies or Andes.
Figure 2: Different pressure patterns of upper atmosphere defining the Polar vortex.
The most likely cause of the Wave sequence is sinuosity or the sine wave pattern that develops whenever there is flow through a uniform medium. For example they occur in the Gulf Stream/North Atlantic drift as it crosses the Atlantic. In this case it’s the faster river of air of the Vortex flowing through the upper atmosphere.
There are two patterns (Figure 3); Zonal with a few low amplitude waves and Meridional with high amplitude waves. The number of waves varies most in the Meridional flow where the amplitude determines the north south extent of the wave. This is the pattern creating the current weather.
Figure 3: Rossby Wave patterns. Source: Briggs, Smithson and Ball et al.
Related Weather
The number and pattern of the waves is important in determining the type of weather patterns in the middle latitudes (35° to 65°). Cold air is denser than warm air, which means it determines what happens in these latitudes. Cold air advances pushing the warm air out of the way or warm air moves in as the cold air retreats. Zonal flow provides less variable weather, fewer north and south winds, and generally more predictable prevailing winds and weather. Meridional flow gives much more variable weather, more north and south winds and generally less predictable weather. It appears the pattern changes when the world is cooling. The cold air advances
We know Rossby Waves move from west to east usually at a relatively steady speed. As a result any station in the middle latitudes will generally experience the weather associated with being in the warm or cool air for approximately 4 to 6 weeks. We know when the Waves get large in amplitude blocking occurs and the weather patterns instead of lasting 4 - 6 weeks can double to 8-12 weeks. People become very uncomfortable as droughts, very wet, hot or cold conditions persist. This has been the pattern throughout 2010. Some call blocking systems Omega Blocks because it looks like the Greek letter omega Ω on the weather map.
Figure 4: NASA Temperature anomalies for July 20-27, 2010 Source
Compare the pattern of warm and cold regions in Figure 4, which was the situation across Eurasia from July 20-27, with the map in the bottom right corner in Figure 2. An extreme meridional pattern exists but the vast majority of the land area is cool. The blocking pattern has resulted in warmer air persisting over eastern North America, Western Europe and then latterly central Europe and Russia.
This blocking pattern is critical for the continued claim of record warm in 2010. Figure 5 shows the distribution of weather stations used to establish the global temperature average. Concentration of stations in the middle latitudes of the Northern Hemisphere is 69% of the total. The stations they choose emphasize the distortion. For example, they use one, urban heat island compromised, station for the entire country of Nepal.
Superimpose a meridional pattern of Rossby waves so that the warm areas include eastern North America and Western Europe and the distortion of the global temperature average is obvious.
Figure 5: Distribution of weather stations showing vast gaps. Source
As the cold air pushes toward the Equator it comes in contact with warm moist tropical air. This triggers severe weather including thunderstorms, tornadoes and very heavy rain.
The pattern is starting to change as the Wave pattern shifts. We’ll continue to hear about extremes claimed as evidence of warming. In reality, they’re evidence of cooling all with known and natural causation. When will they face the facts?
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