These two applets plot the changes in insolation values and orbital parameters of the earth with time.

Applet 1 displays the insolation values for two given months and the specified range of years.
If any of the months is set to zero, it will plot the daily variation of insolation values for the two given years. (Click on "COMPUTE" to display the graph for the first time. Year 0 is 1950. Day 0 is the vernal equinox)

Applet 2 plots the cange of orbital parameter with time. Omega is the precession of the moving perihelion.

The values are calculated following Berger, A. L. 1978 Long-Term variations of Daily Insolation and Quaternary Climatic Changes. Journal of the Atmospheric Sciences, vol. 35, pp. 2362-2367.

At this moment the code does not check for absurd values, so check your inputs. It only works properly for latitudes where the sun rises and set. I will consider an extension soon. Recommended resolution of the screen: 1024 x 768 or higher.

An Excel worksheet with the equations can be downloaded here.

OrbitTerms.java has the core routines in java for the calculation of the orbital parameters.

Solarcalc is a insolation calculator for direct and difusse radiation at any given latitude and terrain orientation.

Comments are welcome

Insolation Values according to latitude and year

Click on the "compute" button to start. Set any month to 0 (zero) to compute daily insolation values.