PowerPoint Presentation - Cosmic Rays

Tyler Thiele
Cosmic rays are high energy charged
particles, in outer space, that travel at nearly
the speed of light and strike the Earth from all
directions. Most cosmic rays are the nuclei of
atoms, ranging from the lightest to the
heaviest elements in the periodic table.
Cosmic rays also include high energy
electrons, positrons, and other subatomic
89% protons (hydrogen nuclei)
10% Helium nuclei
1 % Electrons, heavier elements
Extra-solar cosmic rays (all those except
those emitted by the sun as solar flares), also
known as Galactic Cosmic Rays, originate and
are accelerated to nearly the speed of light by
supernovae explosions.
The cosmic rays that arise in extra-solar
astrophysical sources are primary cosmic
rays; these primary cosmic rays can interact
with interstellar matter to create secondary
cosmic rays. The Sun also emits low energy
cosmic rays associated with solar flares.
Cosmic rays were first discovered and coined
by Victor Hess in 1912. He detected radiation
in the upper atmosphere using an
electroscope in a balloon. To determine
whether or not the radiation was coming
entirely from the sun, he repeated the
experiment during a nearly complete solar
Hess determined that “essentially, the sun
could not be the source of cosmic rays, at
least as far as the undeflected (by the solar
eclipse) rays were concerned.”
Hess was awarded the Nobel Prize in 1936 for
this discovery.
Following the discovery there was a debate
between American physicists Robert Millikan
and Arthur Compton about the nature of the
cosmic rays.
Millikan asserted that cosmic rays were
composed of high energy photons (bases of
electromagnetic spectrum), while Compton
claimed that they were composed of charged
particles. Compton was eventually proven
Following an experiment which involved
cosmic rays passing through a cloud
chamber, it was further proven that cosmic
rays behaved like charged particles when
passing through a magnetic field in the cloud
chamber and therefore are not a form of
electro-magnetic radiation.
Flux: number of particles per unit area per
The flux of cosmic ray particles as a function of
their energy. The flux for the lowest energies
(yellow zone) are mainly attributed to solar
cosmic rays, intermediate energies (blue) to
galactic cosmic rays, and highest energies
(purple) to extragalactic cosmic rays
When cosmic ray particles enter the Earth's
atmosphere they collide with molecules,
mainly oxygen and nitrogen, to produce a
cascade of lighter particles, a so-called air
shower. The general idea is shown in the next
figure which shows a cosmic ray shower
produced by a high energy proton of cosmic
ray origin striking an atmospheric molecule.
Cosmic rays ionize the molecules in the
atmosphere, which leads to a number of
chemical reactions, including the ionization
of water.
Due to its lacking of empirical evidence, the
theory that solar variation has a significant
effect on the climate (by affecting cloud cover)
has been overshadowed in favor of the
“politically correct” man-made greenhouse gas
Cosmic rays could be the link between solar
variation and cloud cover on earth, and
therefore have a significant effect on the
When clouds form they contain millions of water
droplets in each cubic meter of air. Each of the cloud
droplets forms on a particle. A collection of particles is
called an aerosol. In cloud formation, one particle
produces one water droplet, so there are the same
number of particles as there are water droplets.
The aerosol particles come from natural processes as
well as human activities. They are made of soil, dust,
and sea salt, or from air pollution from cars, power
plants, and factories. During cloud formation, water
vapor (which is also contained in air) condenses on the
aerosol particles.
Charged water droplets combine with aerosol
particles 10-100 times more efficiently than
uncharged ones.
Thus the ions created by cosmic rays entering
the atmosphere will enhance the efficiency of
cloud formation.
Correlation Between Cosmic
Ray Flux and Cloud Cover.
Cosmic rays fit as the mechanism for the
aforementioned solar theory, because the
cosmic ray flux on the earth is dependent on
solar activity. The Earth’s magnetic field also
plays a part in deflecting cosmic rays.
The sun and the Earth both have magnetic
fields that deflect incoming cosmic rays. This
divides cosmic rays into three categories:
Low energy rays that are deflected by the
Earth’s magnetic field.
Medium-energy rays that are deflected by
the sun’s solar wind and/or magnetic field.
High energy rays that are not deflected by
either field.
60 % of the ionized particles that originate
from GCRs are from the high-energy
category, and therefore cannot be blocked.
However, the other 40% come from medium
energy GCRs and therefore are under
the influence of the solar wind and
the sun’s magnetic field.
Total cloud cover (solid red line) and low cloud cover (broken blue line) as
obtained from infrared (low clouds) and visual plus infrared (total cloud)
observations. The thin black line represents the Climax Cosmic Ray Flux
scaled for comparison.
Cosmic rays are a likely link between solar
activity and earth’s temperature.
The sun regulates 40% of the GCR spectrum
(and that 40% is more likely to strike the
Earth). As this 40% varies with solar activity,
so then does cloud cover and temperature.
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