photo courtesy NASA
Orbital variations of insolation values
These two applets plot the changes in insolation values and orbital parameters of the earth with time.

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.

There is plenty of information on the topic at: The World Data Center A- Paleoclimatology, which publishes insolation values for the last 5 million years.

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. 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.

Orbital Parameters of the earth

Javier G Corripio
Now at jgc
Last modified: Wed Feb 13 13:18:50 GMT 2002