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The patterns that give rise to freezes in citrus areas of the United States have a pronounced periodicity when placed into the context of eclipse rhythms. In order to make sense of the eclipse rhythms however, it is necessary to understand the concept of a jet curve. When an eclipse occurs, it is possible to project the longitude of the celestial event onto the longitude of the earth. This can be done by placing Greenwich (0°) longitude at 23° Aries. This forms a band of longitudinal sections placed at 30° intervals that effectively projects the Zodiac onto the earth. Using this as a foundation the celestial position of an eclipse is used as the originating or seed point. From this eclipse point the following curves can be generated.
If a compass is set with one end on the eclipse point, and the other end set on 72° degrees of arc from the eclipse point and a curve is drawn, the curve will describe a curved latitudinal meridian in a specific longitudinal zone. This zone is a place in which the polar jet stream tends to form loops in a given year. Another curve can be drawn from a point set at 45° degrees of arc from the eclipse point. This is the place of another polar jet loop for the time until the next eclipse shifts the point to a new longitude. These two curves are known as jet curves and they can be used as a significant indicator of the activity of the jet stream in a given year.
Figure 1 illustrates the formation of two jet curves, one at 45° of arc and another at 72° of arc using an eclipse point as the center of the generating circles. In a given winter the polar jet tends to track along these curves when forming blocks that are stable, high- pressure ridges of air. As a result, the position of the eclipse point in a particular year can give indications of where blocks of high pressure will be likely to form in the northern hemisphere westerlies. In general, cold air tends to flow down the east side of a block due to the clockwise circulation of winds in the block. This is illustrated in figure 2. In the drawing the blocks are labeled H for high pressure and the gray ribbon snaking through the atmosphere between the blocks is the jet stream that is flowing from west to east. Where the jet rounds across the top of a block cold air is being brought down from the north into the south. This is the source of citrus freezes when the blocks are situated in such a way that the polar jet can drop the cold into California or into Florida.
The concept in this essay that is central to the understanding of citrus freezes is the observation that the position of the eclipse point that generates the jet curve enables the polar jet to drop cold into the longitude that will damage the citrus trees. Further, this positioning in semi-decadal (4.5 yr.) and decadal(9.5 yrs.) periods can be predicted by noting the retrograde motion of the eclipse points through the zodiac. the following case studies of well known citrus freezes in California will illustrate this concept.
1913 / triple eclipse / eclipse point 13 Virgo.
1974/75 / Nov 74 -eclipse points 20 sco /5 sag.
1990 / Dec 21 freeze - eclipse point 18 Capricorn.
1998 / Dec freeze - eclipse point 20 Capricorn.
In California the strongest, not necessarily all, citrus freezes have occurred when the eclipse points were between Scorpio and Leo. In 1913 the grand daddy of citrus freezes almost wiped out the fledgling citrus industry on the West Coast just as it was getting started. One eclipse point was in Leo. This is illustrated in figure 3. The gray arrow is the cold pouring down out of the north following the 72° leg of the double jet curve.
In December 1975, another citrus freeze year, the November eclipse point was in Libra. This is illustrated in figure 4. In that year the cold followed the 45° leg of the double jet curve with the same result of cold air flowing south along the jet curve as depicted by the gray arrow. In the fall of 1990 the eclipse point eclipse point was in the middle of Capricorn. This created another jet curve pattern in which the eclipse point is over the Atlantic instead of the Pacific.
However, in this next chart, figure 5, we can see that the 45° curve would guide a looping jet stream trough down the West Coast from British Columbia. As a result in December 1990 a strong citrus freeze unfolded in southern California along the jet curve. This freeze started on December 21, 1990 and extended for two weeks into January 1991.
The next citrus freeze started on December 20, 1998 and lasted for a week killing many trees in California. The eclipse position was once again over Central America putting the 45° jet curve parallel to the West Coast of North America. This pattern is depicted in figure 6. The high pressure from the 45° jet curve pushed up into Alaska and strong cold descended into California. The placement of the jet curve off of the west coast determines the placement of the polar jet stream. In this instance the offshore placement of the jet curve pulled the jet offshore and allowed the cold to descend.
The last image is the current situation for the winter of 2007. The position of the eclipse points is very close to the position of the points in 1913. The blocking pattern this fall has been one in which a dominant Hawaii High in the longitude of Hawaii has consistently kept the east Pacific jet stream moving to the north while keeping the southern portions of the West Coast cloud free. The pattern of temperatures has been quite polarized with daytime temperatures going into the middle sixties in the daytime and the very low thirties at night. Jupiter has been influential in the latest cold spell, working to support high pressure from a position just east of Hawaii. It is very interesting to note that in 1913 Jupiter placed very close to the current position.
This pattern of blocking should reach a peak this coming week as the predicted daytime temperatures begin to dip to the low fifties with night time temperatures moving into the middle twenties in the valleys of California. This is due to the dislodging of a very cold Siberian air mass last week that is now approaching the coast as a very cold front. Doc Weather feels that this is the beginning of a very different winter pattern so stay tuned. In the short term this return of the strong cold may be a threat to the citrus trees in California in the next few days.