The Seasons

It’s solstice time in a few days, so here is an infographic on the seasons (click for hi-res image):

Infographic constructed using R (with DescTools::DrawCircle, rasterImage, layout, and the suncalc package for day length calculation). Images used are a diagram by “Colivine,” paintings by Arthur Streeton and Joseph Farquharson, and two photographs of my own.


Phenology wheels

Recently, somebody pointed me at phenology wheels, which are a popular tool for nature study among teachers and homeschoolers. Nature study is all about careful observation and finding patterns, and phenology wheels help with both. Every month, students draw a picture of what they see in the garden or on a nature walk, and the completed phenology wheel then shows an annual pattern. Other activities are possible – see this University of Wisconsin-Madison Arboretum document.

The picture below shows a pair of partially complete mother/daughter phenology wheels from the very useful Nature Study Australia website (they are using the central circle to show indigenous seasons). It is helpful to outline each month’s section in felt-tip pen:

Mother and daughter phenology wheels from

I’ve generated blank wheels for the Northern Hemisphere and for the Southern Hemisphere, and produced a partially complete wheel of my own (from a European perspective):

Like nature journals, this is an activity both fun and educational!

Credits: lavender watercolour painting by Karen Arnold, sunflowers by Vincent van Gogh, butterfly from here, font is Jenna Sue, wheel constructed using R (with DescTools::DrawCircle, rasterImage, and the showtext package).

World Solar Challenge: Weather in Darwin

One very helpful input to race strategy in a solar car race is weather expertise. How much sunshine can we expect? And when can we expect it? In 2013, Solar Team Twente took along an expert from the Joint Meteorological Group of the Royal Netherlands Air Force to help with that. This year, Punch Powertrain Solar Team (team 8) is taking along an expert from the the Royal Meteorological Institute of Belgium, who will be blogging his insights and experiences.

For those without his specialist expertise, forget everything you thought you knew about Spring and Summer, Autumn and Winter. Darwin has 7 seasons, as the Larrakia People tell us, and the World Solar Challenge begins towards the end of Dalirrgang (the “Build Up” – click image above for multimedia tutorial). Dalirrgang is a kind of overture to the rainy season (the “Wet”). Traditionally, Dalirrgang is the time to hunt the Magpie goose (photo by Djambalawa below).

Long-term weather forecasts suggest that the World Solar Challenge this year might in fact begin on a partly sunny day, with a little rain, but that’s very uncertain, this far ahead.

No wonder it’s cold down here

Here in Australia, it’s the middle of winter. And, as Bad Astronomy reminds me, we’ve also just had aphelion, Earth’s furthest point from the sun (152 million km, compared to 147 million km at closest approach). The diagram below exaggerates the elliptical nature of Earth’s orbit, but it gives the general idea:

For the current distance to the sun, see Wolfram’s calculator or the live diagram of the solar system at Fourmilab, which includes images (green lines show orbits below the plane of the ecliptic):

Live Solar System image