Presentation on theme: "The study of Earths atmosphere. Weather vs. Climate Weather: Wind, temperature, precipitation, cloud cover and air pressure. Can be localized. Climate:long-term."— Presentation transcript:
The study of Earths atmosphere
Weather vs. Climate Weather: Wind, temperature, precipitation, cloud cover and air pressure. Can be localized. Climate:long-term wx conditions over a large area. Classification based upon temp. and precip.
Atmosphere Composition: 78 % Nitrogen 21 % Oxygen.036% Carbon Dioxide* Rest: water vapor; dust; ozone; argon * Has the most impact, meteorologically speaking
Refer to Atmosphere Layers Hand Out (A)Troposphere: up to ~12km. Where we live, where wx occurs. Temp.as altitude. Rate of change: 6.5 o C/km. Thinnest layer (B)Stratosphere: ~12km-50km Contains the O 3 (Ozone) Layer
Stratosphere contd As elevation increases, temperature increases due to the absorption of radiation by the O 3 Layer UV rays + O 3 O 2 + O O 3
Ozone Layer and Stratosphere contd This rxn in the O 3 Layer causes UV rays to get absorbed. If the rxn is disrupted (as in below), then holes in the O 3 layer form. This allows more UV rays to reach the earths surface, increasing skin cancers, etc. UV rays + O 3 O + O 2 + CFCs CFCO + O 2 The result: Depleting the Ozone Layer so there is less Ozone to react w/the UV rays, more UV rays get to Earths surface
Layers and layers continued C.)Mesosphere: extends to 80 km. As altitude Temp. Upper part called mesopause. Avg temp. -90 o C
Just one more layer………. D.)Thermosphere: ( km) contains the ionosphere in its lower portion. Temp. increases as altitude increases due to the absorption of short-wave, high- energy solar radiation
Not quite done yet…………. Auroras occur in the ionosphere. Energetic electrically charged particles (mostly electrons) accelerate along the magnetic field that surrounds the Earth. They collide with gas atoms and solar radiation, causing the atoms to give off light.
Heat Transfer Conduction: transfer of heat through matter by molecular activity. Energy is transferred through collisions of one molecule to another
Heat Transfer Convection: the movement of matter due to the differences in density which is caused by differences in temp.
Heat Transfer Radiation:transfer of heat energy through space via electromagnetic waves. Electromagnetic waves can travel in the absence of matter (mechanical waves, like sound, can not).
Meet ROYGBIV ( Not who….what) ROYGBIV stands for the electromagnetic spectrum (light) R=Red O=Orange Y=YellowY=Yellow G=GreenG=Green B=Blue I= Indigo V=VioletV=Violet When white light (from the sun) is separated (like a rainbow), it separates into these colors
Wavelength long short Yellow RedOrangeYellow Green BlueIndigoViolet VISIBLEVISIBLE LowFrequency – EnergyHigh infrared Ultra-Violet
Weather Principles and Vocab……
! Pressure= Force/area Pressure is measured in Pascals (Pa) 1 Pa = 1 Newton (force)/m 2 (area) AIR PRESSURE is measured in milli bars (mb) 1 mb = 100 Pa Standard air pressure at sea level = mb (aka 29.9 inches of mercury)
What is needed for precipitation? Temp. of pocket of air >Temp. of environment ( Tp>Te) This causes: Temp. of pocket of air >Temp. of environment ( Tp>Te) This causes: Vertical transport, which causes Instability.. Need pocket of air to rise in order for it to cool, condense and precipitate Vertical transport, which causes Instability.. Need pocket of air to rise in order for it to cool, condense and precipitate Condensation/Moisture. USUALLY 75% relative humidity Condensation/Moisture. USUALLY 75% relative humidity
THEREFORE….. IN GENERAL, precipitation will not occur when a high pressure system is in control. If the pressure is high, then the air SUBSIDES (sinks)….if it sinks will not get the instability, etc needed for precipitation.
So what do you get w/a high pressure system? USUALLY…fair weather, light winds Tp
What gives bad weather/precipitation? IN GENERAL, a LOW PRESSURE system Tp>Te, causing the air to rise, get the instability, condensation, etc
Low Pressure System Pressure is low so the surrounding air pressure, in contrast, is high.Pressure is low so the surrounding air pressure, in contrast, is high. High pressure wants to go to lowHigh pressure wants to go to low That replacing air rises….causes the instability and condensation needed for precip/poor wxThat replacing air rises….causes the instability and condensation needed for precip/poor wx
What causes Pressure Differences? Temp. differences Density differences Pressure differences
So……WHAT causes the temp differences??????? Uneven heating/ cooling of the Earths surface. These cause AIR MASSES that then cause FRONTS/FRONTAL SYSTEMS
Maritime Polar(mP) Continental Polar cP) cP mP Maritime Tropical (mT) Continental Tropical (cT) mT Air Masses Page 603 in book
Air Masses Names and Properties Maritime Polar (mP) Continental Polar (cP) Continental Tropical(cT) Maritime Tropical (mT) Moist (from off the ocean), cold from the poles Dry from off the continent(land), cold from the poles Dry from off the land; warm from equator Moist from off the ocean, warm from the equator
FRONTS Warm front Cold front COLD AIR WARM AIR
Warm Front Incoming air is warmer (less dense)than air it is replacing Warm over runs air it is replacing Often get cirrus clouds as warm front approaches Can get precip. Usually not violent(ex: showers, drizzle)
Cold Front Incoming air is colder (more dense) than the air it is replacing Replaced air rises quickly Get precip that could be violent (thunderstorms, tornadoes)
Stationary Front Unsettled wx stalls. Usually drizzley Overcast
Occluded Front Cold front catches up to warm front Weather can be VERY violent (more than a cold front) thunderstorms, tornadoes
Definitions: Dewpoint:The temperature at which air becomes totally saturated w/water Humidity: amount of water vapor in the air Relative Humidity: airs water vapor content to its water vapor capacity. Capacity can change w/temp. HOW/WHY? (temp.capacity )
Formula for RH Yeah!!! Math in Science Relative Humidity (RH)= Absolute humidity/Capacity X 100=% Ex: at 10 o C capacity is 11.0g/cm 3 The actual humidity(absolute)might be 5.5g/cm 3, so…… 5.5/11 x 100=50% RH