Cycles on the Sun
The sun is not the center of gravity of its solar system. Jupiter and Saturn are the two biggest of the sun’s planets. They combine with the sun to effectively define the center of mass of our solar system, the barycenter for the rest of the sun’s planets. Rain comes from evaporation. The amount of rain that falls is a function of the amount of heat from the sun which has caused the prior evaporation, which is a function of the positions of the orbiting planets. Over a longer period the amount of solar radiation varies as to what we call the sunspot cycle. These are what have been noticed as spots that appear on the sun.
The spots on the sun represent energy transfer between planets and the sun. It is why astronomers, particularly in China have been counting sunspots for centuries, and they have seen that the solar cycle is not perfectly regular. Solar activity swings back and forth like a pendulum. At one end of the cycle, there is a quiet time with few sunspots and flares. At the other end, solar maximum brings high sunspot numbers and solar storms. It’s a regular rhythm that repeats roughly every decade. In the past century peaks have been 2001-2, 1989-91, 1980-81, 1968-70, 1957-59, 1947-48, 1936-38, 1925-29, 1917-19 and 1892-94.
Sunspots are like perpetual storms on the sun and their cycles depict times of increased solar activity, leading to solar energy arriving on earth. The cyclic swing in sunspot counts can take anywhere from 9 to 14 years to complete; also, the amplitude of the cycle varies. Some solar maxima are very weak, others very strong. Generally the cycle averages out to be 11 and 22-23 years. Frequently higher sunspot-counts of around 150-200 were during cycle 8 in 1836, cycle 18 in 1947, cycle 19 in 1957, cycle 21 in 1980 and cycle 22 in 1990, which show a roughly 11-year functionality.
Increased solar activity is responsible for some of the warming in the first half of the 20th Century. Solar activity started increasing around 1910 and reached a maximum around 1960 with cycle 19. After that it remained, on average, higher during the second half of the 20th Century than during the first half. It was higher for most of that time than at any time since the 1790s.
Whilst the timing of cycle-phenomena of sunspots is regular, amplitudes are less so. Drought years have been during declining SS cycles in 1918-20, 1938-46, 1982-83, 1991-95 and 2002-4, and during inclining SS cycles of 1935-38 (severe droughts in NSW, SA and WA), 1965-68, 1976-78, 1987-89. The wetter years have often been between those years and seem to be just before solar peaks, some being 1999, 1990-91, 1988, and 1970.
The last two solar maxima, for cycle 22 around 1989 and cycle 23 around 2001, have had not one but two peaks. Solar activity went up, dipped, then resumed, each time performing a mini-cycle that lasted about two years. There is a similarity between cycle 24, underway now, and cycle 14, which also had a double-peak during the first decade of the 20th century.
Cycle 14 spanned 1902-10 and peaked in 1904-6 and 1907-8. If the two cycles are twins, it would mean one peak in late 2013 and another in 2015. 2013 is, in this comparison, on a par with 1905-6. The same dipping in peaks could be happening now. Sunspot counts jumped in 2011, dipped in 2012, and are expected to rebound again in 2013 possibly lasting into 2014.
Currently, solar activity is relatively low, below what it was in 2011, and strong solar flares have been infrequent for many months. Climate trends affect hemispheres. Australia and NZ have been hot, also many parts of southern Africa had their hottest January on record, while the month was also much hotter than normal in large parts of Argentina, Chile and Brazil. In parts of Patagonia, January temperatures were more than 4°C above normal.
A low solar count leads to slackening of evaporation needed for rain. Australia’s longest drought 1958-69 saw sunspots rarely reach above 100, as had also happened between 1911-16. In 2008 the word ‘drought’ was banned in Australia as it was considered too upsetting for farmers. Both 2008 and 1913 were years 70-80% clear of sunspot activity.
The so-called Maunder Minimum (between 1645 and 1715 when very few sunspots were observed) coincided with the "Little Ice Age", during which Europe and North America were subjected to bitterly cold winters, when the Thames froze over and people walked about on the frozen river surface, even holding fairs. Some scientists hypothesize that the dense wood used in Stradivarius instruments was caused by slow tree growth during that cooler period. Instrument maker Antonio Stradivari was born a year before the start of the Maunder Minimum.
Without a high sunspot count we head for drought in inland areas. By looking to see which years in the past correspond at the same point of the sun cycle to the year in question we can compare past figures and come up with a usable result for the amounts of rain we can expect in any given year. When we combine solar cycles with lunar, we arrive at a workable set of years to compare past weather to.
The years 1995-8, 1977-8 and 1925/26 were equivalent to 2013 and were years of both late monsoon seasons and of heavy bushfires in the south of Australia. In NZ 1996 was a wet year, and 1977 saw March rains dispel the dry previous two months then a wet winter. 1925/26 saw many floods throughout the country. This year we are approaching the first peak in cycle 24, a wet indication. Although it does not feel possible with the current dry conditions, it could yet turn out to be a wetter than average year.
Ken Ring of [www.predictweather.com|www.predictweather.com] is the author of the Weather Almanac for NZ for 2013 (Random House publisher)
