Search results
Results from the WOW.Com Content Network
Upper-atmospheric lightning is believed to be electrically induced forms of luminous plasma. The preferred usage is transient luminous event (TLE), because the various types of electrical-discharge phenomena in the upper atmosphere lack several characteristics of the more familiar tropospheric lightning.
Tropospheric ducting is a type of radio propagation that tends to happen during periods of stable, anticyclonic weather. In this propagation method, when the signal encounters a rise in temperature in the atmosphere instead of the normal decrease (known as a temperature inversion), the higher refractive index of the atmosphere there will cause the signal to be bent.
Free tropospheric temperature refers to the temperature in the upper layers of the troposphere where the influence from the surface and the boundary layer is negligible. Although the framework is formulated with the gradients of free tropospheric temperature, this phenomena occurs as a result of gradients and fluctuations in buoyancy .
Positive lightning is less common than negative lightning and on average makes up less than 5% of all lightning strikes. [ 10 ] A bolt from the blue lightning strike which appears to initiate from the clear, but [ clarification needed ] the turbulent sky above the anvil cloud and drive a bolt of plasma through the cloud directly to the ground.
Global map of lightning frequency--strikes/km 2 /yr. The high lightning areas are on land located in the tropics. Areas with almost no lightning are the Arctic and Antarctic, closely followed by the oceans which have only 0.1 to 1 strikes/km 2 /yr. The map on the right shows that lightning is not distributed evenly around the planet. [5]
When a series of lightning strikes took down power across New York City on the night of July 13, 1977, streetlights, neon signs, and the bright lights of houses and skyscrapers went dark.
However, they are cold plasma phenomena that lack the hot channel temperatures of tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges. Sprites are associated with various other upper-atmospheric optical phenomena including blue jets and ELVES .
Typically, lightning discharges 30,000 amperes, at up to 100 million volts, and emits light, radio waves, x-rays and even gamma rays. [1] Plasma temperatures in lightning can approach 28,000 kelvins. Atmospheric electricity describes the electrical charges in the Earth's atmosphere (or that of another planet).