On 2009 Jun 25, at 18:52 , Irv Bromberg wrote:
To my surprise, and in direct contradiction to Mike's assertions otherwise, in terms of daily average temperature, the actual data shows that there is no seasonal lag -- the chart clearly shows that the maximum average is reached around the time of the north solstice (red), temperature falls off slightly by the time of the southward equinox (brown), the coldest average is reached around the time of the south solstice (blue), and temperature starts to rise by the time of the northward equinox.
(Irv sheepishly adds, very red-faced...)
OK, I went back and fit a sine wave to all of the Toronto average temperature data 1995 to date.
The Sine( ) expression is: Temperature = HalfSpan x SinDegrees( SolarLongitude - Lag) + AnnualAverage
The temperature swings ±15°C (HalfSpan=15), with the annual average at +8°C, and to obtain the best alignment of the sine wave peaks relative to the temperature peaks, I needed to include a lag of about 35 days = 5 weeks. (This is pretending that each degree of solar longitude is one calendar day, which is close enough.)
The daily solar longitude was calculated for noon in Toronto.
Therefore if a 5-week month starts at a solstice, then the next month will on average start at the seasonal extreme.
Well, I'm off to the couch to eat my hat...
-- Irv Bromberg, Toronto, Canada
