Sun Spots


Solar Wind

Solar Magnetic Mean Field


The Solar Irradiance is a measure of the energy of the electromagnetic radiation emitted by the Sun at all wavelengths. The Solar Irradiance is found strongest when the solar activity is at a maximum, which is a result of two competing processes.
The presence of Sun Spots on the solar surface blocks out radiation and causes a decrease of the Irradiance. This is compensated by the fact that other magnetic regions known as plagues and faculae emit excess radiation. Overall, the effect is that more radiation is emitted at a solar maximum.
The energy we receive from the sun is one of the most important factors for life and the climate on earth. However, the observed changes in the total solar irradiance during the last solar cycles are so small that they are not expected to have any significant influence on our climate. Long term variation of the solar irradiance could on the other hand play an important role in climate evolution.

The data used here are daily averages of the solar irradiance measured by a variety of spacecrafts. To be more precise, it is the version d25_07_0310a of a datapack obtained from PMOD/WRC, Davos, Switzerland and uses unpublished data from the VIRGO Experiment on the cooperative ESA/NASA Mission SoHO. For more details see:
C.Fröhlich and J. Lean, 1998, "The Suns Total Irradiance: Cycles, Trends and Related Climate Change Uncertainties since 1978", Geophys.Res.Let., 25, pp. 4377-4380, 1998

The size of the inner circle as well as the colour correspond to the Irradiance and are smoothly changed from one measurement to the next. Interpolated values can be identified by the thin line surrounding the inner circle. The colour of the outer circle jumps from one measurement to the next.

The value of the Irradiance measurement changes the sound of a cello and a violin, the higher the value of the Irradiance, the more the original sound of the strings are altered.