Updated at 23 Jun 2026
Natural electric fields, like the Earth's atmospheric field ('Fair Weather Field') of 100-300 V/m, are influenced by the global ionospheric circuit and atmospheric ionization. Thunderstorms generate significant potential differences leading to lightning, sprites, and jets, while ionization layers enable long-distance radio communication.
Static electric fields and forces arise when electric charges are spatially separated, such as through friction between two insulating materials (triboelectricity). Examples include the static charge build-up when removing plastic sweaters or friction between clothing and car seat covers, leading to small electric shocks upon discharge. Natural voltage differences also exist between different metals, utilized in batteries to generate direct current. At the Earth's surface, a permanent electric field known as the "fair-weather field" exists, with strengths varying between 100 and 300 V/m depending on time and local conditions. This field is generally attributed to the global atmospheric electric circuit, which circulates between the Earth's surface and the ionosphere at 70-80 km altitude. Thunderstorms produce this potential difference by separating charges within clouds, functioning like atmospheric batteries. Typically, the upper parts of thunderclouds are positively charged and lower parts negatively charged, though the exact mechanism of charge separation remains debated, involving processes such as charge transfer during collisions between different hydrometeors and ion exchanges. Updrafts driven by condensation energy facilitate these dynamics. Voltage differences between clouds and ground can become large enough to create electrostatic discharges (lightning), which regulate charge imbalances. Lightning also occurs between clouds and the conductive upper atmospheric layers, maintaining a predominantly positive layer. Intra-cloud lightning is more frequent than cloud-to-ground strikes. Thunderstorm activity is most intense in tropical regions; outside these, ionized particles (ions and free electrons) maintain a steady vertical electrical current of about 1 cm/s. The precise drivers of the global electric circuit remain uncertain; besides thunderstorms, diffuse charge flows from falling aerosols might contribute. Ionospheres form due to solar radiation ionizing atmospheric gases; positive ions and free electrons accumulate primarily at 300-400 km altitude where recombination rates are low, enabling persistent ionization even during nighttime. This layer reflects shortwave radio signals worldwide continuously, facilitating global communication via radio waves.
