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AVIATION METEOROLOGY • Meteorology is the science that study the atmosphere and atmospheric phenomena. “Meteo” means “something in the sky” in Greek and “Logo” means “to describe, to express, to say”. • Weather is the state of the atmosphere (parameters of atmosphere) at a specific period of time and with respect to its effect on life and human activities. It is the short term variations of the atmosphere, as opposed to the long term, or climatic, changes. It is often referred to in terms of brightness, cloudiness, humidity, precipitation, temperature, visibility, and wind • Atmosphere is the gaseous or air portion of the physical environment that encircles a planet. • Aviation Meteorology (AM) is the branch of science that study influence of meteorological variables and atmospheric phenomena on aeronautical engineering operation. AM develops methods and forms of meteorological service of The main periods of Aviation Meteorology Development Period 1st period Term 1910 – 1940 Period characteristics Use of near earth observation data, surface weather chart, indirect methods of meteorology, sounding balloon data about fair weather wind 1910 – First weather station was organized in Sevastopol on the base of military pilot school. 1921 – Main weather station was founded 1922 – Aeronavigation office was founded at Moscow airdrome to provide meteorological service of pilots. Method of radiosensing of atmosphere was developed under the direction of Molchanov. This method is the basis of baric topography chart composition that is the tool of weather analysis. The main periods of Aviation Meteorology Development Period characteristics 2nd 1940period 1960 Pressure topography charts, weather reconnaissance data, centralized information data of weatherforecasting service, scientific study of weather hazards at different cruising altitude are widely used. 3rd 1960period till our days Further equipment of weather services operation; wide application and development of Weather radar, weather artificial satellites and electronic calculators for processing and indicating weather data. Computerbased systems of meteorological service of flights are made. ATMOSPHERE STRUCTURE AND COMPOSITION Composition of the Atmosphere Gas Name Chemical Formula Percent Volume Nitrogen N2 78.08% Oxygen Water * Argon Carbon Dioxide * Neon Helium Methane * Hydrogen Nitrous Oxide * Ozone * O2 H2O Ar CO2 Ne He CH4 H2 N2O O3 20.95% 0 to 4% 0.93% 0.0360% 0.0018% 0.0005% 0.00017% 0.00005% 0.00003% 0.000004% Structure of the Atmosphere • According to the influence on aircraft flight operation Atmosphere is divided into - specific atmosphere (up to 150 km) - near-earth space. • According electrical properties Atmosphere is divided into - ionosphere - neutrosphere • According to the Atmosphere chemical state it can be - Homoshere (about 80-100 km height) – chemical composition is almost constant - Heterosphere Thermal Structure of the Atmosphere Troposphere (temperature decreases with height), Stratosphere (temperature increases with height, the presence of Ozone layer ), Mesosphere (temperature decreases with height) Thermosphere (temperature increases with height, high kinetic temperature) Exosphere International Standard Atmosphere (ISA) ISA has been defined by the ICAO as a mathematical model that involves all parameters affecting the flight of an aircraft, its performance and general behavior under special conditions. Standard Atmosphere is a hypothetical vertical distribution of temperature, pressure and density that are taken to be representative of the atmosphere for the next purposes: Purposes of Standard Atmosphere 1) Manufacturing, graduiating and calibrating pressure or speed related instruments like altimeters, mach meters, pitot tube etc. 2) To design and test aircraft Elements of the ICAO Standard Atmosphere At Mean Sea Level (MSL) Air temperature Atmospheric pressure Air density Molar mass of air Gravitational acceleration Relative humidity Vertical temperature lapse rate 15 C or 288,15 K 760 mm of mercury or 101 325 Pa 1,225 kg/m3 28,964 kg/kmol 9,8066 m/s2 0 0,65 C/100m Above MSL The temperature in the stratosphere is assumed to be constant (with height) Lapse rate From MSL to 36 00 feet 2 C/1000 feet 36 000 feet upwards 0 C/1000 feet