Simulations / Earth & Space Science

Seasons Over Detroit

Earth's 23.4° tilt changes the Sun's height and the length of the day. Slide through the year and compare Detroit with other latitudes.

Controls

The eight Lab cities follow the city you choose in the header or on the City Explorer. The last four are reference latitudes.
Formulas: declination ≈ 23.44° × sin[360°/365 × (day + 284)]; noon altitude = 90° − |latitude − declination|; day length from cos H = −tan(lat) tan(decl). These approximations are accurate to within about one degree. Intensity index = noon sine of altitude relative to Detroit's summer solstice.
Date
Noon Sun altitude
degrees above the horizon
Day length
hours
Shadow of a 1 m stick
meters at noon
Noon sunlight intensity
vs. Detroit summer solstice

Try this

  • Find Detroit's noon altitude on each solstice and equinox. Do they match your lab calculation?
  • Switch to Anchorage. What happens to day length in summer and in winter?
  • Switch to Sydney. Why are the seasons reversed?

What to notice

  • On the equinoxes the Sun is 90° − latitude above the horizon at noon.
  • The same beam spread over a longer shadow means less heating per area.
  • At the equator the Sun is nearly overhead twice a year and day length barely changes.

Connect to the lab