4st PART


Our planet is bombarded with cosmic particles (nuclei of atoms) OF high-energy from other stars and supernovas. These are cosmic rays. The magnetosphere deflects the most of cosmic rays but some arrive in the atmosphere and there it cause reactions. At the magnetic equator low energy particles are returned back to space by the Earth's magnetic field at the magnetic poles, but the particles of all energies can follow the field lines down to the top of the atmosphere. Scott E. Forbush The physicist remarked in 1937 that solar flares mitigate the flow of cosmic rays. This has been proven by the Pioneer probe 5 in 1960 and it's called the Forbush effect. So when solar activity is at its maximum, the Earth receives less cosmic rays and during the minimum of solar activity the Earth receives more cosmic rays.

At the maximum of solar activity of Schwabe cycle the solar wind prevents these particles to reach Earth while during the minimum of solar activity the solar wind is less important then the Earth's atmosphere gets more cosmic rays. The change in the amount of cosmic rays received by our planet is approximately 20% between the maximum and minimum solar activity.

Cosmic rays with an energy of :

  • 108eV are of low energy and are produced by the Sun
  • 1015eV are produced by supernovae
  • 1017eV are produced by pulsars
  • 1018eV are produced by galaxies with active nucleus (?)
  • 1020eV sare produced by unknown stars


This diagram shows the monthly number of sunspots (dotted line) and
the intensity of cosmic radiation (solid line). Note the anti-correlation
between the intensity of cosmic radiation and solar activity.


Three Danish researchers (Knud Lassen, Eigil Friis-Christensen and Henrik Svensmark) think they have explained how the climate is influenced by the sun. From data of 1984 to 1990 of three satellites they concluded that the variation of cosmic rays entering the atmosphere was the same as that of cloudiness. Then in 2011 the results of the CERN experiment called CLOUD have shown that cosmic rays multiplied at least tenfold the production of nucleus. However even if it is true that these cosmic rays have increased the clouds by a factor of ten, even with that effect, it is still far of the concentration needed to explain the condensation of the clouds. For in the report of CERN/CLOUD they tell us: "Second, we found that the natural rate of atmospheric ionization, resulting from cosmic rays, can amplify the nucleation in the conditions of our work (NdT : It's say with only traces of sulfuric acid and ammonia) by a factor of up to 10. The amplification by the ions is particularly pronounced in the cold temperatures of the middle troposphere and above, where CLOUD found that sulfuric acid and water vapor can nucleate without the addition of additional vapor.
This result leaves open the possibility that cosmic rays may influence the climate. However, it is premature to conclude that cosmic rays have a significant influence on the climate as long as additional nucleating vapors have not been identified, their rate of amplification by the ions has not be measured and their ultimate effect on clouds has not been confirmed.

The clouds that form at low altitude are relatively warm and composed of fine water droplets. They would cool the planet by reflecting sunlight back into space. But the clouds created in high altitude, are colder as they are composed of ice particles and have the opportunity to warm the earth by trapping heat.

According to satellite data since 1980, Henrik Svensmark and Marsh ND have concluded that mostly the lowest clouds (within 3 km altitude) vary the most according to the intensity of cosmic radiation.

These three diagrams show the percentage of change in the cloud coverage of high altitude (above 8 km altitude), medium altitude (3-8 km), and low altitude (below 3km) from 1983 to 1994 (thin lines). On each chart was recorded the number of neutrons it is the inverse of the variation in solar activity (thick lines) representing the flow of cosmic rays entering the atmosphere. The change of the low cloud cover following the flow of cosmic rays that vary with the solar cycle of 11 years.
(G. Campbell data and C. Lopate. Updated by E. Friis-Christensen by personal communication with Marsh and H. Svensmark N. 6 March 2000, NASA Research Workshop on Climate and Sun in Tucson, first Arizona.)..

Here the same comparison between the intensity of cosmic rays
(red curve)and the curve of the cloud coverage for low level (blue curve)

but this time from 1980-2005. Source : ESA Space-weather

When cosmic particles enter the atmosphere they should attract molecules of air and thus should facilitate the condensation of the water vapor of the atmosphere into the form of clouds according these researchers. Then according to data from the ERBE (Expérience sur le Budget du Rayonnement Terrestre) satellite launched in 1984, the clouds cool the Earth by absorbing and reflecting a certain amount of solar radiation. So albedo of the Earth is stronger at the minimum of the solar cycle than at its maximum.

For our planet the albedo is on average 30% :

  • 5-10% on the seas cloudless

  • 10 to 15% above forests

  • 30-50% on deserts

  • 60 to 85% on snow and ice

Depending on the amount and types of clouds, albedo of the Earth is very different. The clouds reflect more light back into space as the cloudless sky. the size and thickness of clouds, and the size and number of droplets inside the cloud vary the cloud albedo.

The clouds composed of large drops of water or with lots of water droplets reflect more light back into space.

The albedos of clouds various according to J. Gourdeau :

8 %
20-40 %
40-65 %
75 %
90 %

Clouds have an albedo superior than of the surface of the Earth without clouds. So they reflect more sunlight back into space than does the Earth without clouds so there is less energy available to heat the Earth's surface and atmosphere.


The variation of cosmic rays entering the atmosphere, varying according to
solar activity, could affect the Cloud layer. Source : CLOUD Experiment CERN


The Sun is our most important energy source. The solar constant is 1368 W/m2. So the average energy received by the Earth from the poles to the equator is the fourth of the solar constant is 342 W/m2.

On the 342 W/m2 received on Earth from the sun only 160 W/m2 reach the ground because 102 W/m2 are reflected (82 W/m2 by the atmosphere and 20 W/m2 by the Earth's surface) and 80 W/m2 are absorbed by the stratospheric ozone, the water vapor and the tropospheric carbon dioxide.

For that the Earth reach a temperature of 59°F (15°C) it should 390 W/m2. The 330 W/m2 missing are provide by the atmosphere and constitute what is called the greenhouse effect.

But it has not be found the mechanism that does that a small variation in the Sun's energy causes significant climate change.

Of the french magazine
Ciel & Espace

When solar activity varies it's the ultraviolet emission which changes the most. The variation of the ultraviolet contributes to 30% to the variation of the solar constant and has effects on the stratospheric ozone layer. At the minimum of Schwabe cycle the Earth receives less ultraviolet that leads to create less ozone in the stratosphere, when at the maximum an increase of 1 to 2% of the ozone concentration is produced. This last contributes to the greenhouse effect by absorbing infrared and therefore there this could explain elevation or drop in temperature during maxima and minima of the Schwabe cycles.

There are also effects on the biosphere, the temperature of the stratosphere (thermal and dynamic balance) capable of bringing changes into the troposphere, the atmospheric circulation and cloud formation. When solar activity is at a maximum and that ozone is most abundant, it would warm the stratosphere, would intensify the circulation of the Hadley cell, would shift mid-latitude depressions to the north and would replicate the latest results of Labitzke and Van Loon.

Change in the stratospheric ozone layer (in Dobson units) from data TOMS
(Total Ozone Monitoring Spectrometer) on the latitude 65°N-65°S. The line
dashes represents the solar cycle of 11 years with annual average solar flux. The
volcanic eruption of Mount Pinatubo in June 1991 is indicated to show the effect.

The astronomer Karin Labitzke also has noted the links between mood of the sun and direction of QBO in the stratosphere with the climate at the poles and at midlatitudes. Click here for more information about it.

A relationship between the duration of Schwabe cycle and the surface temperature since 1860 has been found. The longer the solar cycles are the less high solar activity is and therefore the solar constant is less important. Which decreases the temperature on the earth.

the curve of length of changes of solar cycles (red) and the variations in
temperatures in the northern hemisphere (blue) are virtually superimposed. This
suggests that when the cycles getting shorter, temperatures rise. This phenomenon
could be explained by the fact that the maxima of activity cycles, so closer, produce
a denser solar wind and limite the formation of clouds in the atmosphere.

The temperature varies from about 32,72°F (0,40°C) with a change of 4 W/m2 de la constante solaire. of the solar constant. This is the difference between the minimum Dalton (1795 to 1830) and 1980.

Besides all this, the variation in solar activity also affects sun radiation and in turn it has effects on the climate of the Earth.


According to the concentration of carbon 14 and beryllium 14 measured in ice cores, there is a period of 2300 years. The origin of this variation (Hallstattzeit cycle) is not yet well known but it is not nevertheless excluded that the Sun (due to carbon 14) or even ocean circulation participates. The minimum of this cycle coincides with the Maunder minimum. So that by 3950 there could be a next little ice age. Currently the Hallstattzeit cycle is growing and its maximum should be reached around the year 2800. Some researchers believe that this could be the cause or one of the causes of global warming.

During the Little Ice Age, the Thames River in London froze in winter during
the 17th century. This print depicts the icy river in 1683-1684.
This coincided
with a period when there was very little sun spots and hence low solar activity


temperature in °C


Click to enlarge


The movement of gas planets makes vary the angular momentum of the Sun around the barycenter of the Solar System. All the 179 years the angular momentum of the Sun varies very quickly like that was the case during the Maunder Minimum. That could slow the large convection internal currents of the sun suspected by some scientists to influence the variation of solar activity. At a low solar activity the diameter of the Sun is more important, and its speed of rotation is lower by about 3% than the current speed. When solar activity get weaker the brightness does the same as it was the case during the Maunder minimum, as the brightness should have been lower of about 0,2 to 0,3% than now. More solar activity wanes, the higher the magnetic field and the solar wind weaken and therefore the extension of the Earth's magnetic field is reduced. This allows to more of cosmic rays to enter in the atmosphere. And so increases cloudiness because cosmic rays promote the formation of clouds at low altitude which increases the albedo and thus also reduces the brightness and radiation from the Sun on Earth.

During the Maunder Minimum the total solar irradiance long time called "the solar constant" was lower by 0,25% compared with current period which is 4W/m² which has had the effect of lowering the temperature 32,45°F (0,25°C). While ultraviolet (UV) radiation which are only about 1% of the solar radiative output their variation is more important than the total solar irradiance. During a variation of 0,25% of total solar irradiance relative to now, the UV vary around 10%. The UV have much effect on the atmosphere. Increasing the temperature of the ionosphere is around 300% between the minimum and the maximum of the solar activity cycle of 11 years. So with a major change such as between the Maunder Minimum and now UV must have varied so much that it could have had enough effect on the chemistry of the stratosphere (the ozone layer ...) and its dynamic.

Therefore when a major variation of several solar cycles that last in average 11 years according to long term cycles of Suess cycles or Vries, the combination of the changes of solar radiation, of UV, of brightness, of magnetic field, of solar wind and therefore of cosmic rays , must be one of the causes of the evolution of the temperature in the atmosphere.

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