ATMO 336 1st Edition Lecture 22 Outline of Last Lecture I. Monsoonsa. Subtropical highs and monsoonal highsb. In terms of Tucson II. 500mb pattern and air flow during the monsoon season in TucsonIII. increases in water favor during monsoon seasonIV. impacts of extreme events in the USV. trends in sever weather deaths and damages in USVI. long term trends in world wind extreme weather eventsVII. two perspectives on recent trends in extreme weather eventsVIII. heat waves and cold wavesOutline of Current Lecture II. Ozonea. Good ozone vs. bad ozoneIII. Summary for stratospheric ozone depletiona. CFC’sb. Measured loss of stratospheric ozonec. The ozone “hole”IV. Dangers of UV radiationa. Classes of radiationV. Effects of UV exposure on skina. Melenaoma and skin cancerb. UV protectionCurrent Lecture- Ozoneo Form of oxygen that comprises of O3 (rather than O2)o 90% of it between 6 and 10 miles above earths surface and extends up to 30 miles.= Stratosphere contains ozone layer ozone in upper stratosphere and lower stratosphere are chemically identical, buthave different roles (good ozone= absorbs most of damaging UV radiation while creating source of heat, forming the actual stratosphere) bad ozone= ozone near surface of earth, toxic to humans (naturally little concentrations at surface but increased due to human activities)= photochemical smog- Summary for stratospheric ozone depletionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o CFC= chlorofluorocarbon= methane molecule Contain chlorine and/or bromine, when released they can destroy ozone and remain in atmosphere for 100 years. CFC broken up by exposed to high levels of UV Chlorine and bromine capable of destroying up to 100,000 ozone moleculeso Since 1979, measured loss of stratospheric ozone has been 10% at high latitudes 5-10% at middle latitudes little change for tropics destroyed in homogeneous chemical reactions (gas phase chem. Reactions) between chlorine (or bromine) radicals and ozone.  Depletion of ozone via homogenous chem. Is relatively lowo Ozone “hole” Large depletion of stratospheric ozone over Antarctica (up to 70% depleted) from late September through early December (spring in southern hemisphere) Result of complex chem. Reactions only happen under extreme cold conditions in Antarctic (take place on the surfaces of ice crystals in polar stratospheric clouds when temp is below -90 degrees F) Much smaller and weaker ozone hole located over Arctic region, but don’t happen as they do in Antarctic stratosphere Size of ozone hole in Antarctic varies year to year due to differences in atmospheric conditions in winter and early spring. Measurements show the holeis stabilized and improving, but full recovery wont be until middle of this century Most likely, non of us have been exposed to dangerously high levels of UV radiation due to ozone depletion. Skin cancer depends on lifestyle (use of sunscreen, sun exposure, ect.)- Incidences of melanoma have been increasing though, has little to do with ozone depletion. Has more to do with self responsibility and protection.- Dangers of UV radiationo Radiation= form of energy transporto Photon= smallest amount of radiation energy that can exist (cannot be broken down) The hotter the object, the more photons it emitso Object absorbs radiation by absorbing photons UV has enough energy to disassociate molecules due to the amount of photons it emits o Classes of radiation UV-c - Most energentic and damaging to cells- All UV-C from sun absorbed by ozone and oxygen in stratosphere and doesn’t reach surface UV-B- Most absorbed by ozone in stratosphere but significant portion does penetrate ground- Linked to 90% of skin cancers- Reduces growth and heath of ocean phytoplankton, damages early dev. In fish and other aquatic species- Damages and stresses land plants  UV-A- Least energetic UV photon- “tanning rays’- long term exposure can lead to skin damage (photoaging or “leathery” skin) and perhaps skin cancer (not proven) - effects of UV exposure on skino depends on where photons are absorbed if UV-B absorbed by outer dead cells, no problem since those cells are for protection if UV-B absorbing by living cells, can damage (sunburn) if cells have insufficient melanin (tan pigment in skin cells that absorb UB before reaching nucleus) If UV-B absorbed by cells responsible for producing new skin cells,the following can occur..- Can be stimulated to produce more melanin to protect cells- Calls can be damaged to where they can no longer produce (DNA damage or skin cancer with uncontrolled growth of mutant cells)o Melanoma can be detected early (before it spreads) using “ABCD” self- examination A- asymmetry B- border irregularity C- color variation D- diameter> 0.25 inches ( size of a number 2 pencil eraser)- Notes on UV protectiono SPF= sun protection factor is a measure of how much longer a person can safely stay in sun with sunscreen compared to without sunscreen. (SPF 15= safe 15X longer)o Lying under umbrella or shade is not enough protection since UV photons are reflected form sand and watero High altitudes or mountain locations are more dangerous than a location at sea level since UV photons can be absorbed or reflected back up by air molecules before they reach the surface of eartho Sun angle is an important factor= the closer the sun is to straight up, the greater the UV exposure (sun angle smaller near equator and larger near poles) Min. sun angle in northern hemisphere occurs on june 21st Max sun angle in northern hemisphere occurs on December 21st If shadow is shorter than your body, you need uv protectiono UV exposure is not dependent on temp (can burn on a cold day equal to that on a hot day)o Thin clouds (cirrus clouds) allow enough UV radiation to get through so burning occurso Skin cancer in Southern Arizona highest in the US (lots of sun, low latitude, high altitude,clean atmosphere with low relative humidity)o UV index= forecast each day. Ranges from 1-15 (15 being most UV exposure). Calculations consider: Sun angle at noon (depends on latitude and time of year) Current amount of ozone overhead Cloud cover Concentration and size of aersols in atmosphere (these can reflect or absorb UV