Radio atmospheric a distance where luminosity is visible and thunder can be heard (typically about 10 km), these electromagnetic impulses are the only sources of direct information about thunderstorm activity on the ground. Transients electric currents during return strokes (R strokes) or intracloud strokes (K strokes) are the main sources for the generation of impulse-type electromagnetic radiation known as sferics (sometimes called atmospherics). While this impulsive radiation dominates at frequencies less than about 100 kHz, (loosely called long waves), a continuous noise component becomes increasingly important at higher frequencies. The longwave electromagnetic propagation of sferics takes place within the Earth-ionosphere waveguide between
Atmospheric wave Atmospheric wave An atmospheric wave is a periodic disturbance in the fields of atmospheric variables (like surface pressure or geopotential height, temperature, or wind velocity) which may either propagate ("traveling wave") or not ("standing wave"). Atmospheric waves range in spatial and temporal scale from large-scale planetary waves (Rossby waves) to minute sound waves. Atmospheric waves with periods which are harmonics of 1 solar day (e.g. 24 hours, 12 hours, 8 hours... etc.) are known as atmospheric tides. The mechanism for the forcing of the wave, for example the generation of the initial or prolonged disturbance in the atmospheric variables, can