The excess charge on the surface of the earth is a result of the Earth's atmosphere being constantly bombarded by cosmic rays, which are high energy particles. These particles can either knock electrons off of atoms, resulting in a net positive charge, or add electrons to atoms, resulting in a net negative charge.
The excess charge on the surface of the earth can be measured using a device called an electroscope. This instrument detects the presence of electric charge by measuring the repulsive forces between two charged objects.
The amount of excess charge on the surface of the earth is affected by several factors, including solar activity, atmospheric conditions, and the Earth's own magnetic field. Solar activity, such as solar flares, can increase the amount of cosmic rays bombarding the atmosphere, resulting in a higher excess charge. Atmospheric conditions, such as thunderstorms, can also affect the amount of excess charge due to the buildup of static electricity. The Earth's magnetic field can also influence the amount of excess charge by deflecting some of the cosmic rays.
The excess charge on the surface of the earth is generally not harmful to humans, as our bodies are able to conduct and dissipate this charge. However, in rare cases, the buildup of static electricity from the excess charge can lead to lightning strikes, which can be dangerous. It is important to take precautions during thunderstorms to avoid being struck by lightning.
Scientists and researchers are constantly studying the excess charge on the surface of the earth in order to better understand its effects and potential risks. This includes monitoring solar activity, measuring atmospheric conditions, and using advanced instruments to study the Earth's magnetic field. By gaining a better understanding of this phenomenon, we can better predict and prepare for potential hazards, such as lightning strikes.