An Inexact Science
THURSDAY OCTOBER 01, 2009
Really weather is an opinion-based product based on best-guessing, from blending available information into experience, just like economics or political science. It is reasonable to allow for a 24hr error in the actual arrival of rain. Many things can hold rain up, such as the levels of cloud not yet matching with the layers of cold air that will bring condensation, or heat from the ground stopping rain from falling.
Weather systems do not move at uniform speed, anymore than wind does. Faster systems mean more changeable weather - terrain, elevation and proximity to coastlines determining just how much so.
There is further potential skewing in the summer cyclone season because cyclonic activity can take over by developing a life of its own, temporarily sucking great amounts of upper air to one side, like a whirlpool in a bath's plughole. This occurs from December to May in the southern hemisphere. Equinox months March and September are especially error-prone due to the distortion and subsequent twisting of the atmosphere by the Sun, and the greater impact of the solar air-tide.
The reality is that weather is generated between 200 ft and 8 miles up, which means a potential overshoot of a rain system in a radius of up to 50-60 miles. So if a forecast says rain for Auckland but it only rains in Huntly, 60 miles away, given the tools available it is as close as one can reasonably get, and should therefore be considered a successful forecast. For coastal locations it can mean a rain dump might land away out to sea. In a district such as Mangawhai, the error range and the fair range of applicability potential is, if we take 60 miles as the crow flies, somewhere north to the Bay of islands and south about as far as Auckland.
Most weather readings, averages etc are taken at airports. Airports are usually windier, which the planes need to be able to take off with, and then land again safely, and being windier are therefore drier places than hills or nearby towns. Unless your location is at or near the airport the forecast may be at least slightly (and possibly way) out. This is not a problem in an unchanging landscape but may be one in a varying terrain whereby a farmer living high on a hill or in a valley can't understand why the airport data didn't tally with what weather occurred on his farm, yet in the same breath he may be aware of his own small microclimates around particular mounds, hills, valleys and flats. Of course we can't have a data-gathering station every few metres.
What we have lost in this age of automatic weather stations is the input of experienced human interpretation. A weather apparatus may register small amounts of rain on an automatic gauge, but that may only be dew, frost, non-recordable rain and even dense fog. A gauge cannot distinguish as well as an on-the-spot human who is familiar with the vagaries of the area. Also, errors of amounts are often a function of elevation, where rain can get confused with mist.
Rain amounts rely on the prior evaporation rate which is due to the heat of the Sun. The Sun only provides heat and cannot cause rain, especially at night. The evaporation cycle can be anywhere between 3-11 days with convective summer falls, but in cooler climates and seasons may be about 7 days from sunshine to rain falling. Timing of rain depends on the movement of high and low pressure zones, air flows and air streams, and movement and positioning of cooler and warmer air layers, which are all influenced by the Moon exerting a tidal pull on the atmosphere.
When calculating weather from the Moon I am looking for repeatable Moon factors. They are Moon speed, angle of rising, moonrise and set times, height in the sky at zenith, phase, declination, closeness to Earth, ocean-tide times and heights, barometric pressure on the day, and closeness to equinox and solstice. One Moon cycle does not apply equally everywhere. Full moon effects are more potent in the tropics. The Moon moves very quickly and whilst weather systems do change more quickly when the Moon is moving faster relative to the earth, they do not change as fast as the Moon, which in an hour moves 15 degrees of longitude and half a degree of latitude. It is the aspects that the Moon makes with Sun and planets that have greater effect. There is a general overlay of weather for a region on a particular day, but as one approaches ground level, variations in weather become more evident, and topography determines the weather "personality" of a valley. Areas with less changing terrain usually have less weather variation over a wide area.
In all places there are specific local error potentials, depending on latitude, elevation etc. In NZ we encounter specific limitations of having to work with "island" weather, with its shift of weather types at the shore-line, and strong bias by an ocean surrounding, short durations over land, and other problems associated with smaller land masses. There are no inland deserts to generate extreme heat, and vast dry spaces like the desert SW of the USA or across the Australian Interior. Australia has what might be called continental patterns. Weather systems down here can be quick to come and quick to go, the westerlies and SWs predominate and can bring sudden shifts and changes which can delay or hasten predicted arrivals of events forming in the Tasman Sea. Cycles do rule and the hazard to the forecaster is that the potential may also recycle for the same error each time it comes back around.
Bearing in mind all the above may lead to a fairer analysis, but the interpretation is still the responsibility of the end user and not the method. All the method constitutes of is a set of tools. The hammer manufacturer cannot be blamed for your bruised thumb. If an inaccurate forecast is given, that does not invalidate the moon method but might just mean this author is still learning. One does not throw away all hospitals because one doctor errs - better wisdom uses the mistake to revise procedures. One should never expect that one method or approach is the answer to all one's prayers. One has a duty to obtain all the knowledge one can from widely varying sources, and also apply one's own personal experience. This sounds obvious but in this day and age we are delegating to others and we demand instant panaceas and foolproof systems. Perhaps we blame others if things go awry rather than ourselves for making bad choices at the outset. Generally one area has its own local peculiarities, and these should be the backgound canvas onto which forecasts are cast.
Having said all that, there do seem to be some interesting rules. When the moon changes hemispheres in its 27.3 day declination cycle, barometric pressures can be observed to change. Locations furthest south in winter are more affected by southern ‘declination’, and this is mainly parts of SA, VIC, TAS, S NSW, also for the South Island of NZ, which is neighbouring the South Pole. The top half of Australia is less affected by southern declination, and sometimes even warms due to more anticyclonic patterns. Conversely in the south, the northern declination is relatively ineffective in winter, but in summer can bring significantly hotter temps to central and more northern parts of Australia.
Remember the 13th of March 2008 in Adelaide? Officially the hottest maximum ever recorded there. Northern declination was on the 13th at 9pm. The Adelaide heatwave lasted 3 weeks. Could it be an amazing coincidence that the day of March's northern declination, the day the Moon was the furthest north, exactly matched the day of hottest mean Adelaide temp reached in March? Well then how about April, when the hottest Adelaide day(9th) was within one day of northern declination, or February, when the hottest day (19th) was within two days of February's northern declination? Are these all coincidences? For the all-time record, Australia's highest EVER recorded maximum temperature was on 16 January 1889, at Cloncurry. Was it northern declination that day? Yes, absolutely. So why Adelaide? I cite Adelaide because I have good historical data for that city, data which is very sparse or non-existent for NZ towns.
It is hard to quantify weather events exactly because the locations on the land are not standardised. There are differences in elevation, direction-facing, extent of hills, proximity to coast and terrain variation. You can’t put any of that in a test tube and hold it over a Bunsen burner. To that extent any rigorous scientific assessment of any method is just not viable. There are simply too many variables for the scientific method to be applied. But you can look ahead and put rings around the calendar and roughly expect certain weather at particular Moon event times which is what the ancients did. That is the awareness we are trying to spread, so we can all plan weather patterns for our own areas more effectively.
About the only legacy we seem to be leaving future generations at the moment is that weather is bizarre, unfriendly, unpredictable, and because of that we must pay extra taxes for boneheaded scientists to endlessly research it, under the label of 'climate change'. As part of that package of untruths it seems to be acceptable for greedy corporates and corrupt politicians to control the price of energy, and it seems equally acceptable that the poor and elderly die of starvation, cold because they cannot afford heating, and lack of medical care.
I ask that we bring back the weather wisdom of the Moon, learn and apply it for ourselves and for our livelihoods, and teach it to our children. We can at least leave them that. Let us teach them that the Moon comes in cycles and as does the tide so does the weather, and these cycles can be quantified. It is not perfect and no one has all the answers, but we can use the Moon's cycles to make useful predictions as to trends. We should not expect too much. As good and effective as any method is, it is our responsibility to also plan for alternative outcomes.