meteorology

=The study of the entire atmosphere including its weather.=

The atmosphere
=Structure of the atmosphere=
 * air is a mixture of many gases in earths lower atmosphere
 * nitrogen and oxygen together form about 99% of dry air by volume
 * The remaining 1% is mainly argon and carbon dioxide

Troposphere - is the lowest layer of the atmosphere (0-12KM) in which all of earths weather occurs

 * Gradually decreases in temp with an increase in altitude
 * contains all water vapor
 * The jet stream is located between (6-12KM)


 * Steady winds and few weather changes (planes fly here)
 * steady increase in temp with the increase of altitude which is caused by absorption from the ozone

Thermosphere - Temperature rises again about 500 Km from earth


= What is the weather like outside? = = Weather - is the state of the atmosphere at a given tie and place= =To try to predict weather you n= =eed to observe the clouds, wind, temp,humidity, and pressure and precipitation over a period of time= = = = Heating of the atmosphere- energy from the sun results in changes in the weather. heat moves through the atmosphere in three ways= = = = = = Insolation = = Solar energy - that reaches the earth; we receive one two billions of the sun= = = = = = =
 * Conduction - An object receives heat when it comes in contact with a hotter object (Ex. a pan on a hot stove)
 * radiation - Hot bodies radiate energy in short waves (sun); Cold bodies radiate energy in long waves (earth)
 * Convection - most effective; the rising of hot air and sinking of cold air results in a steady flow. convection is very important in moving heat through the atmosphere



= = = Green house effect - Short ultra violet waves from the sun are able to reach the earths surface. then longer infrared waves re-radiated by the earths surface are trapped by green house gasses (CFC's and CO2) Normal lapse rate - the rate of cooling with altitude (1 degree c every 160 meters) Temp inversion - when the air is especially still cooler air, because of its greater density settles close to the ground and the warmer air forms a blanket above it. In a temp inversion pollutants in the = = air such as smoke and soot are also trapped close to the ground = = = = Specific heat - The amount of heat required to raise the temp of something 1= =degree C=

**water has a very high specific heat compared to soil** Absorption - to take in energy and heat up Reflection- to bounce back energy Re-radiation- to absorb short wave energy and give off long wave energy Good absorbers poor Absorbers

=Heating of land and water=

=Which heats up faster ??=

= =

= Water warms much more slowly than land =


 * =In water the sun's rays go to a depth of many meters. on land only the top few centimeters of soil is heated by the sun=
 * =water can spread heat easily because it is a fluid=
 * =some solar energy is used in the process of evaporation thus less solar energy=
 * =water cools more slowly than land because its heat is spread through a greater depth=

= Temperature = = Temp- is a measure of the energy of molecules the more energy the molecules in air have the hotter it feels= = = = Isotherms- are lines drawn on maps connecting places with the same temperature= = = = evaporation- the change from liquid from liquid water to water vapor= = = = humidity- the capacity of air for holding water vapor= = psychrometer- is the instrument used to determine relative humidity=
 * Temp is measured in degrees (celsius,fahrenheit,kelvin)
 * Thermometers are the instrument used to measure temperature
 * the alcohol expands when heated
 * Thermographs are self recording thermometers
 * =as air temp increases so does the amount of water vapor it can hold=
 * =specific humidity- the amount of water vapor=
 * =relitive humidity- compares the acully amount of watery vapor in the air with the max amount of water vapor the air can hold at that temp=

= condensation- the change from water vapor to a liquid this occurs when the temperature drops low enough that the capiticy for water vapor in the air drops below the specific humidity.=

=Example-= = dew -water vapor which condenses on surfaces such as grass in the form of a liquid=

= dew point- temp at which saturated water occurs= =air may be cooled below its dew point in many ways=
 * contacting a colder surface
 * radiating heat
 * mixing with colder air
 * expanding when raises

=water vapor needs to condense on something!!= = condensation nuclei - tiny particles such as salt, sulfate, or nitrate particles on which water vapor condenses= = FOG = =surface layers of air a f= =ew hundred meters thick which are cooled below the dew point. as water vapor condenses tiny droplets stay suspended in the air by the lightest air movement= = Radiation fogs - at night the ground loses heat rapidaly light winds mix the cold bottom air with the air a short distance from the surface when the whole layer of air is cooled below the dew point a fog forms (common in humid valleys and near rivers and lakes)= = advection fogs - results when warm moist air blows over cool surfaces (ex coastal California)=
 * =when cooling occurs by contact with a colder surface the water vapor condenses directly on that surface >0 deg c =dew=

= clouds- clouds form when air above the surface cools below the dew point= = Precipitation- is the falling of any form of water from the air to the earths surface= = types of precipitation: =
 * =occurs when clouds droplets grow into drops heavy enough to fall to earth=
 * = Raindrops- form from tiny droplets and then grow by bumping into and combining with other droplets=
 * = sleet- forms when raindrops fall through the freezing air and fall to the ground as pellets of ice=
 * = hailstones- begin as a frozen raindrop and grows by collecting smaller ice particles or liquid or cloud droplets=
 * = acid rain- forms when water condenses on sulfate and nitrate=

= Air pressure- the weight of the atmosphere per unit area= =Differences in air pre= =ssure cause the earths wind and weather changes=

= **PRESSURE DECREASES WITH ALTITUDE** =

= BAROMETER - is an instrument used to measure air pressure=

[[image:borometer.jpg]]
= Aneroid barometer - Measures pressure with a thin metal can= = Mercury barometer - uses mercury to measure the pressure but not used as often= = Millibar - is a metric unit of pressure= =**standard sea level pressure is 1013.2MB**= = Isobar- are lines that join points having the same air pressure at a given time= =*each line is worth 4 MB= = High pressure area - the area of the largest pressure the pressure in a high is greater than the surrounding air= == = Low pressure area - this area has lower pressure than the surrounding area= = Pressure gradient- the rate of change for air pressure between two points= = Rising barometer- greater pressure usually means cooler drier weather (sinking air)= = Falling barometer- less pressure because the air is warm and moist and rises this can be a sigh of precipitation= =WIND-the horizontal movement of air from areas of high pressure to areas of low pressure= =*The closer the spacing between isobars the stronger the winds.= =*winds blow across isobars from high to low air pressure= = Global wind belts -wind flows from high pressure at the poles to low pressure at the equator= =* the wind is deflected by the earths rotation called the coriolus effect*=

== =Air masses= =An airmass is a huge section of the lower troposphere that has the same kind of weather throughtout=

=The best source regions for airmasses= =Air masse have two characteristics= =temp depends on weather it comes from the tropics or polar regions=

=THE HUMIDITY OF THE air mass depends on wheather it comes from land or sea= =Air masses are named from their source region= c-cononitinal (dry) m-maritime (moist) T-tropical P-polar A-arctic = = = = Air Masses An air mess is a huge section of the lower troposphere that has the same kind of weather (temperature and moisture properties) throughout. The best =Boundiries between airmasses are called fronts= =Cold fronts= =1) Cold air is advancing and replacing warm air= =2) cold fronts are steeper and move faster than warm fronts= =3) the air rises upward rapidly forming cumulonimbus= =4) Heavy precipitation and thunderstorms which start and end quickly are associated with cold fronts= =5) precipitition covers 75-100 miles and occurs both befor and after a cold front passes at the surface= =6) cold fronts travel at speeds betweeen 25-30 MPH= =7) as soon as a cold front passes the tempurature will decrease and the wind speed may rise=

= WARM FRONTS =
 * =warm air is advancing and replacing cold air=
 * =warm fronts move slower warm air moves up a gental frontal surface=
 * =warm air may travel 1000 km before rising 2 or 3 km=
 * =First cirrus and cirrostratus clouds form from and then there are altostratus clouds finally steady rain falls from nimbostratus clouds=
 * =precipitation can occur for 225-275 miles ahead of where the front touches the ground=
 * =warm fronts travel at speeds between 20-25 MPH=
 * =warmer temperatures follow the passing warm front=

= Occuled front =
 * =a cold front is advancing and combining with a warm front=
 * =occluding fronts move the slowest of all (20MPH)=
 * =these fronts are associated with cirrus and stratus clouds in front of nimbostrattous and cumulonimbus clouds=
 * =precipitation occurs for about 400 miles most of which is in front of the frontal boundary=
 * =cool air is in front as warm air is forced up by the cold air which follows the passing occulding front=