Biometeorological ApplicationsHeat Stress IndexBased on temperature in humidityDeveloped by R.G. Steadham in 1983Based on evaporative cooling processWhen you get out of a swimming pool the water that evaporates off you occurs in determination of the moisture in the air around youThe more moisture, the fast the evaporationWhen you start mowing your body is sweating it attempt to maintain 98.6F, the evaporational cooling is less efficient because there is already a lot of moisture in the airWhen your body quits sweating you temperature goes upHeat is the number one killer in the United StatesGet a picture of the heat stress chart**Wind Chill IndexDeveloped for polar scientists in the 1940sFor people who experience truly cold weatherUpdated by NOAA/National Weather Service in 2001 for a more meaningful use worldwideTwo factors taken into account in computation are air temperature and wind speedOther important factors are relative humidity and solar radiationClothing and physical body dependentIf you exposed your skin to the open air temperature at low enough temperature your skin will be able to ice and crystallizeThat is what this machine was meant forAbout 80-85% of body heat loss is from the shoulders and upYou can bundle yourself up from the shoulders down and still lose a lot of body heat lossIntro to Atmospheric MoistureWater vapor is probably the most important element in the atmosphere when considering weather and climateThe amount of water vapor (gas) in the atmosphere is highly variable ranging from near 4% near the equator/tropical regions to near 0% in the polar/colder regionsWater vapor is very important when considering atmospheric stabilityThe Hydrologic CycleKnown as the water cycleEvaporationCondensationTranspirationInfiltrationStarts in the water and every day there are tons of evaporation where we go from liquid water to water vaporThis creates very high humidityHumidity is transferred northA lot of the humidity remains in vapor formVery few clouds precipitate, most clouds don’t have ran associated with themCondensation is when some of the clouds rain and it gets put back into the water and there cycle starts all over againTranspiration is plants releasing moisture in the airMoisture/Phase Changes and Latent HeatEvaporation—liquid to gas (heat absorbed)-600 cal/1gram of water, a cooling processCondensation—gas to liquid (heat released)+600 call/1 gram of water, a warming processMelting—solid to liquid (heat absorbed)-80 cal/1 gram of waterFreezing—liquid to solid (heat released)+80 cal/1 gram of waterSublimation—solid to gas (heat absorbed)-680 cal/1 gram of water (example is dry ice)Deposition—gas to solid (heat released)+680 cal/1 gram of waterHumidityRefers to any one of a number of different ways of specifying the amount of water vapor in the airWe can express the humidity in a number of different waysAbsolute HumidityThe weight of the water vapor per volume of air (parcel)Usually expressed as grams of water vapor per cubic meter of airAlso referred to as the water vapor densitySpecific HumidityComparing the weight of the water vapor per volume of air (parcel) with the total weight of the air in the parcel including the water vaporUsually expressed in grams of water vapor per kilogram of airMixing RatioComparing the weight of the water vapor per volume of air (parcel) with the weight of the remaining dry airUsually expressed as grams of water vapor per kilogram of dry airRelative HumidityYou would hear this on the 6 o’clock newsRatio of the air’s actual water vapor content compared with the amount of water vapor required for saturation at a given temperatureExpressed as a percentageTells us about how close we are to saturation…not much about actual moisture vapor content of the airThat percentage doesn’t tell us about the moisture in the air100% humidity doesn’t mean rain, it doesn’t mean clouds, means the air is saturatedThis is measured 5 feet above the groundCan be influenced or changed by:Adding/subtracting moisture to airChanging the given temperatureIn the real atmospheric environment, temperature change affects RH throughDaily temperature changesAir moves horizontally one place to anotherTemperature is 37 in on place and in the other it snowed, air is moved over to the snow covered ground, air is going to turn cooler in the second place, relative humidity is going to increaseAir moves vertically in the atmosphereWhen there is no weather going on it will be most sensitive**?Fog is the result of air being saturatedIf you look at the cloud and you would be in the middle of it and there was fog the relative humidity would be 100%Dew Point TemperatureThe temperature to which a parcel of air would need to be cooled too assuming no change in air pressure or moisture content, in order for the given parcel of air to reach saturationDew point temperature always less than or same as air temperature (if same…air is saturated… RH is 100%)This number tells us how much moisture is in the airMuch more telling concerning the actual moisture content of the airAir/DP temperature close together…RH? Relative humidity is higherAir/DP temperature far apart…RH? Relative humidity is lowerWe measure this 5 feet above the groundThe highest number in the dew point tells us the amount of moisture in the airThe higher the dew point the greater the amount of moistureKnow how to compare and contrast relative humidity and dew point temperature when they are the sameIf there is 1 degree of separation will normally get you 96% humidityYou wont know how to compute relative humidityHumidity Brain TeaserparameterSituation aSituation bSituation cAir temperature92F65F18FDew point temp72F25F17FRelative humidity?%=52%?%=22%?%=96%In which case is the amount of moisture in the air the greatest? A. A because the dew point temperature is the highestIn which case the amount of moisture in the air is the least? A. C because the dew point temperature is the lowestIn which case is the relative humidity the greatest? A. C because they are the closest togetherIn which case is the relative humidity the least? A. B because they are the farthest awayIn situation C the relative humidity is at 96% because they are one point offIn sever weather outbreaks when we have severe thunderstorms it is not the only factor that the base line for average dew point temperature 60 is needed, when dew point is lower than that you wont have severe temperatureThe case when the amount of