density altitude
71Speed of sound — Sound is a vibration that travels through an elastic medium as a wave. The speed of sound describes how much distance such a wave travels in a certain amount of time. In SI Units with dry air at 20 °C (68 °F), the speed of sound is 343 m/s. This… …
72climate — /kluy mit/, n. 1. the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years. 2. a region or… …
73Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… …
74Electromagnetic pulse — Ebomb redirects here. For EBOM, see Engineering bill of materials. This article is about the general weapons effect. For other uses, see the more specific topic (for example, Electromagnetic forming) An electromagnetic pulse (sometimes… …
75Atmospheric reentry — refers to the movement of human made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the edge of space. This article primarily addresses the process of controlled reentry… …
76Rocket engine — RS 68 being tested at NASA s Stennis Space Center. The nearly transparent exhaust is due to this engine s exhaust being mostly superheated steam (water vapor from its propellants, hydrogen and oxygen) …
77Orbital airship — Space blimp redirects here. For airships used in a role similar to satellites, see stratospheric airship. The orbital airship, also called the space blimp, is a proposed space transportation system that carries payloads to and from low Earth… …
78atmosphere — atmosphereless, adj. /at meuhs fear /, n., v., atmosphered, atmosphering. n. 1. the gaseous envelope surrounding the earth; the air. 2. this medium at a given place. 3. Astron. the gaseous envelope surrounding a heavenly body. 4. Chem. any… …
79nuclear weapon — an explosive device whose destructive potential derives from the release of energy that accompanies the splitting or combining of atomic nuclei. [1945 50] * * * or atomic weapon or thermonuclear weapon Bomb or other warhead that derives its force …
80Sun — This article is about the star. For other uses, see Sun (disambiguation). The Sun …
