The piezoresistive effect refers to the change in electrical resistance of a material when it is subjected to mechanical stress. This phenomenon is primarily observed in certain semiconductors and metals, where the resistance changes due to variations in carrier concentration or mobility caused by the applied stress.
Radio atmospheric signals, often referred to as "sferics" (short for "atmospheric radio wave signals"), are low-frequency radio waves generated primarily by lightning strikes during thunderstorms. These signals can propagate over long distances and are detected at various frequencies, typically in the VLF (Very Low Frequency) range, which spans from 3 kHz to 30 kHz.
The Raether limit is a concept in the field of high-energy particle physics and astrophysics, particularly in relation to the behavior of massive air showers generated by cosmic rays. It describes a threshold for the production of secondary particles when a high-energy primary particle, such as a cosmic ray proton, interacts with nuclei in the Earth's atmosphere.
Relativistic runaway electron avalanche (RREA) is a phenomenon that occurs in strong electric fields, typically in the context of thunderstorm electrification, atmospheric electricity, or other high-energy physics systems. It involves the generation of high-energy electrons that can lead to an exponential increase in the number of secondary electrons through a process of ionization and acceleration.
Relaxor ferroelectrics are a class of materials that exhibit a complex dielectric response due to their unique structural and electronic properties. These materials are characterized by their diffuse phase transition, meaning they do not have a sharp transition from a non-polar (cubic or high-temperature phase) to a polar (tetragonal or low-temperature phase) state, as seen in conventional ferroelectric materials.
The Sauerbrey equation is a fundamental principle used in the field of quartz crystal microbalance (QCM) sensing. It relates the change in frequency of a quartz crystal oscillator to the mass of material that has been deposited on its surface. The equation is particularly useful for measuring thin films and mass changes at the nanogram level.
Sprites are a type of upper-atmospheric lightning that occurs high above thunderstorms, typically at altitudes of 50 to 90 kilometers (31 to 56 miles). They are a form of transient luminous event (TLE) and are characterized by their reddish color and tendrils that extend down toward the clouds. Sprites are generally associated with large thunderstorms, especially those that produce powerful cloud-to-ground lightning strikes.
St. Elmo's fire is a phenomenon that occurs during thunderstorms, characterized by a visible blue or violet glow. It is caused by the ionization of air surrounding pointed or sharp objects, such as the mast of a ship or the spire of a church. When the electric field in the atmosphere becomes strong enough, it creates a discharge of electricity that results in a gentle and continuous glow at the tips of these objects. St.
Stoletov's law refers to a principle in the field of photoconductivity and describes the relationship between the intensity of light and the electrical conductivity of certain materials, particularly semiconductors. Formulated by the Russian physicist Alexander Stoletov in the late 19th century, the law states that the photoelectric effect leads to an increase in the electrical conductivity of a material when it is exposed to light.
"Streamer discharge" refers to a specific type of electrical discharge phenomenon that occurs in gases, particularly at atmospheric pressure. It is characterized by the rapid formation and growth of ionized channels, or "streamers," which propagate through the air or other gaseous mediums. This phenomenon is often associated with electrical breakdown in gases, such as during lightning strikes, gas discharges in lighting fixtures, or in other high-voltage applications.
The triboelectric effect is a phenomenon in which certain materials become electrically charged after they come into frictional contact with each other. When two different materials rub against each other, electrons may transfer from one material to the other, resulting in one material becoming positively charged and the other negatively charged. The degree of charge exchange depends on the properties of the materials involved and their position in the triboelectric series, which is a list that ranks materials based on their tendency to gain or lose electrons.
The two-photon photovoltaic (TPPV) effect refers to a process in which two photons are simultaneously absorbed by a semiconductor material, leading to the generation of an electrical current. Unlike the traditional photovoltaic effect, where a single photon creates an electron-hole pair (exciton) that can contribute to electrical conduction, the TPPV effect specifically involves the absorption of two photons such that their combined energy exceeds the bandgap energy of the semiconductor.
Upper-atmospheric lightning refers to unusual electrical discharges occurring high in the Earth's atmosphere, typically above the conventional thunderstorm clouds. These phenomena include various types of high-altitude lightning, such as: 1. **Sprites**: These are large-scale electrical discharges that occur above thunderstorm clouds, typically at altitudes between 30 and 90 kilometers (18 to 56 miles).
Volcanic lightning, also known as "dirty thunderstorms," refers to lightning that occurs within or above a volcanic eruption. This phenomenon is caused by the interaction of volcanic ash and gas ejected during an eruption. The ash particles collide with one another and with other gases, leading to the buildup of electrical charges within the volcanic plume. When the electrical charge becomes strong enough, it can result in lightning strikes.