Question

What are cosmic rays? Explain.
i) Latitude effect
ii) Altitude effect of cosmic rays.

Answer 1

Cosmic rays are high-energy radiation, mainly originating outside the Solar System.Upon impact with the Earth's atmosphere, cosmic rays can produce showers of secondary particles that sometimes reach the surface.

Latitude effect: The variation of cosmic ray intensity (I) with geomagnetic latitude $\left(\theta \right)$ showed that the intensity is maximum at the poles $(\theta ={90}^o)$, minimum at the equator $(\theta =0)$ and constant between latitudes of ${42}^o$ and ${90}^o$. This variation is known as latitude effect shown in figure.
The decrease in cosmic ray intensity at the earth's equator is explained to be due to the earth's magnetic field. The charged particles approaching the earth near the poles travel almost along the direction of the magnetic lines of force. They experience no force and easily reach the surface of the earth and hence maximum intensity at poles. But the charged particles that approach at the equator have to travel in a perpendicular direction to the field and are deflected away. Only particles with sufficient energy can reach the equator, while the slow particles are deflected back into cosmos and hence there is minimum intensity at the equator.

Altitude effect: The peak of the energy distribution is at about 0.3 GeV. The intensity of cosmic radiation increases with altitude, indicating that it comes from outer space. It changes with latitude, indicating that it consists at least partly of charged particles which are affected by the earth's magnetic field.