Florida and California insolation

Insolation is incoming solar radiation at the surface. It depends on the solar constant, the angle of incidence, day length, and what the atmosphere and the ground do with the beam. The seasons lab isolates the first geometry: tilt. The energy-budget lab adds albedo and longwave.

At the December solstice the Sun is overhead at 23.44°S. Miami, at about 26°N, still has a noon altitude near 40°. Day length is close to 10.5 hours. London’s noon altitude is about 15° and the day is under eight hours. Photosynthesis, heating load, and solar yield follow those numbers, not the calendar month.

California’s Central Valley sits near 36°N. Winter days are short enough to matter for fog and for solar, long enough that citrus still works with irrigation. Summer days are long and noon Sun is high — a different energy budget from a Lake District valley at the same season.

Students often say ‘Florida is closer to the Sun.’ It is not, in any sense that matters. Florida is closer to the subsolar latitude in northern winter than London is. That is a tilt-and-latitude sentence, not a distance sentence.

Use the solar-altitude lab with Miami, London, and Nairobi marked. Scrub the date. Nairobi, on the equator, barely changes day length. Miami swings moderately. London swings hard. The three traces are the curriculum.