Final answer:
The Earth's magnetic field reduces the intensity of cosmic rays by trapping charged particles in the Van Allen belts and preventing many from penetrating the atmosphere, particularly at middle latitudes, resulting in lower cosmic ray exposure at the equator compared to the poles.
Step-by-step explanation:
The Earth's magnetic field plays a significant role in modifying the intensity of cosmic rays that strike the Earth's surface. Charged particles, such as electrons and protons from the Sun and outer space, often follow Earth's magnetic field lines instead of crossing them directly. Consequently, this phenomenon results in some particles becoming trapped, forming intense radiation zones known as the Van Allen radiation belts, which are hazardous for piloted space flights and satellites.
Furthermore, the Earth's magnetic field acts as a protective shield, especially at higher latitudes where particles are more likely to enter the atmosphere along the field lines, leading to phenomena such as the Aurora Australis and Aurora Borealis. These displays are the result of cosmic rays ionizing atmospheric molecules, which produces a glow. However, particles approaching at middle latitudes must traverse the Earth's magnetic field lines, which results in many of them being prevented from penetrating the atmosphere and reaching the surface. Hence, the cosmic ray intensity is higher at the poles compared to the equator due to this protective effect of Earth's magnetic field.