Meteorology Ch 1 01 31 2014 Ch 1 ocean and life Meteorology The study of weather variables the processes that cause weather and the interaction of the atmosphere with the Earth s surface Climatology The study of climate including past climate conditions and possible climate changes in the future Weather The condition of the atmosphere at any particular time and place The condition of the atmosphere is expressed according to the following Temperature Humidity relative humidity dew point Pressure Wind Speed and Direction Cloud Cover Precipitation type and amount Visibility Climate The condition of the atmosphere over many years The same variables are used for climate as with weather Climate data use the following Averages normal high 30 year average high temperatures for a given Extremes record high highest temperature ever recorded for a given date and location date and location The Earth s Atmosphere is Relatively thin If you d shrink the earth down to the size of a beach ball the inhabitable atmosphere would be thinner than apiece of paper The Atmosphere Contains various substances Those substances exist in solids liquids and gasses 99 of the Atmosphere Resides Near Earth s surface Why Compressibility Gravity Water Vapor Condensation Evaporation Latent Heat Makes up 0 4 of the Atmosphere Fog Clouds Rain Important for the generation of day to day weather phenomena The process of changing water vapor into liquid water The process of liquid water becoming water vapor Heat released during phase change e g vapor to liquid to ice Thunderstorms Hurricanes etc Important source for atmospheric energy Phase Changes In The Atmosphere They Involve Heat Transfer Gas to Liquid Liquid to Solid Solid to Gas Carbon Dioxide Makes up 0 038 by volume of Earth s Atmosphere o Enters the atmosphere by o Decay of Vegetation o Volcanic Eruption o Exhalation of Animal Life o Burning of Fossil Fuels Beneficial o Absorbing Radiation Harmful o Eye Irritation o Throat Irritation o Vegetation Damage Ozone Makes up 0 01 by volume of Earth s Atmosphere o Provides a Natural Shield for Humans Plants Animals Methane Makes up 0 0001 by volume of Earth s Atmosphere Beneficial o Effective absorber of thermal radiation emitted by Earth s surface Sources o Coal Mines Livestock Rice Fields Gas Pipelines Methane has been increasing 1 for the last 20 30 years Other atmospheric constituents Aerosols suspended solid and liquid particles in the air some are Pollutants Gasses and aerosols in concentration great enough to cause a Dust Salt particles Ash From Forest Fires Volcanoes nuisance or health hazard Nitrogen Dioxide Carbon Monoxide Sulfur Dioxide Ozone Makes up 0 01 by volume 97 of the atmospheric concentration is in the stratosphere Ozone can be beneficial by Absorbing UV radiation Provides a natural shield for human plants and animals High concentrations can cause Eye irritation Throat irritation Vegetation damage Slide 13 on Chapter 1 Weight The force acting on an object due to gravity Weight equals mass times gravity Mass an object s mass is the quantity of matter in an object Consequently the mass of air in an air tight container is the same everywhere in the universe If you were to travel to the moon the effect of gravity is much less that that of the earth but the mass of the air in the container would be the same The weight would decrease but the mass would remain the same Density Determined by the masses of atoms and molecules and the amount of space between them In other words density tells us how much matter is in a given space Atmospheric Density The mass of the atmosphere kg per unit volume m3 at sea level 1 2 kg m3 Slide 14 Ch 1 Pressure The force of the atmosphere acting on an area Pressure force area Air molecules are in constant motion They collide about 10 billion times each second with other air molecules Each time an air molecule bounces against a person it gives a tiny push This tiny force push divided by the area on which it pushes is called pressure Pressure is isotropic force exerted equally in all directions More molecules in a column greater pressure Fewer molecules in a column lower pressure Force mass x acceleration The force in the case of atmospheric pressure is the weight of the air which is the mass of the air times the acceleration of gravity Atmospheric pressure always decreases with increasing altitude Pressure decreases because atmospheric density decreases fewer The air pressure measured in Denver will always be less than the air molecules banging into objects pressure in San Francisco Summary Pressure is the force exerted on a given area Air pressure results when air molecules move and collide with objects Air pressure is exerted in all directions Atmospheric pressure always decreases with increasing altitude The pressure density and temperature of a gas are all related to height each other The atmosphere can be divided up according to pressure 500 mb layer is about halfway up in the atmosphere The atmosphere can also be divided up according to temperature which does not follow a simple relationship with height By averaging out temperature values in the atmosphere we are able to identify 4 layers The layers are identified based on how temperature changes with height Troposphere temperature decreases with height Stratosphere temperature increase with height Mesosphere temperature decrease with height Thermosphere temperature increases with height Separating these layers are lids Tropopause separates troposphere and stratosphere Stratopause separates stratosphere and mesosphere Mesopause separates mesosphere and thermosphere Lapse Rate The rate at which temperature decreases with height Inversion Where the temperature increases with height Average Troposphere lapse rate is 6 5 degrees C per 1000m 3 6 F per 1000 ft rise in elevation Troposphere From the surface up to about 6 10 miles varies with latitude and season higher in the summer and in the tropics Temperature decreases with height because the troposphere is heated by the surface and not by sunlight Almost all of what we call weather occurs in the troposphere 80 of the atmosphere s mass Stratosphere Up to about 31 miles Temperature increases with height because the ozone layer absorbs ultraviolet light and warms up as a result Lack of mixing and turbulence Layered portion of atmosphere strata Very little mixing occurs between the stratosphere and troposphere except with thunderstorms and other strong storms 99 9 of the
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