On the same hot and sunny day you find yourself walking outside with bare feet. Where would you prefer to walk and why? Latent heat of water: As water evaporates from plants (and our skin) it consumes heat from surrounding tissue – cooling the grass – and us. Humid conditions higher atmos. water vapor density and reduced evaporative cooling. Temperature / climate stabilization: Humid maritime climes do not experience the wild daily / seasonal fluctuations of dry desert climes.
Climate Change: The Physical Science Basis
Alan Journet K.A. CONJOUR CONSULTING Ashland, OR alanjournet@gmail.com Cell: 541-301-4107
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Minder / Reminder
Wednesday September 28th, 1:00 - 3:00 pm: "Climate Change and the Rogue Valley of Oregon” OLLI Community Lecture Series presentation in Classroom A at the Campbell Center, 655 Frances Lane, Ashland (the OLLI Offices). This will be an abbreviated summary of the entire course.
The Physical Basis
Reminder of the Questions Weather & Climate The Temperature Pattern From Visible to Heat Waves Earth in a Solar system Historic Notes Atmospheric Gases Carbon dioxide patterns Is Climate Change Unusual? Recent Past Distant Past Relevance? Potential Causes of Climate Change Milankovitch Solar Activity
Imagine a hot and sunny summer day. You hold your hand up to the sun. What do you feel and why? Would you wear white or black? Why?
On the same hot and sunny day you find yourself walking outside with bare feet. Where would you prefer to walk and why?
Weather & Climate
Weather is the mix of events that happen each day in our atmosphere including temperature, rainfall, humidity, severe conditions. http://eo.ucar.edu/basics/index.html
Weather & Climate
Climate in your place on the globe controls the weather where you live. Climate is the average weather pattern in a place over many years. Also deals with temperature, rainfall, humidity, winds. http://eo.ucar.edu/basics/index.html Hence; we refer to the issue as Climate Change - rather than Global Warming
Global Temperatures 1880 – 2010 Goddard Institute for Space Studies 2010 2009 1998 2000-2009 was hottest decade on record http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.gif 2008 Departure from 1961- 1990 mean
Surface Temperature Anomalies 1880-2010 cf 1951 – 1980 mean
http://en.wikipedia.org/wiki/Global_warming
Global Surface Temperatures 2005 cf 1951-1980: Goddard Institute for Space Studies
http://www.ncdc.noaa.gov/paleo/globalwarming/medieval.html Medieval warm period Little Ice Age
The Medieval Warm Period, Little Ice Age, and Now
http://en.wikipedia.org/wiki/Little_Ice_Age Only if we ignore recent data can we argue it’s now no warmer than the MWP http://www.wmconnolley.org.uk/1000_Year_Temperature_Comparison.html 2000 - 2009
Historical Patterns in Temperature
http://www.chatham.edu/pti/Pgh_Env_History/Real01.htm It has been hotter – but not for 2 million years
Higher energy wavelengths IT ALL STARTS WITH INCOMING SOLAR RADIATION Heat wavelengths Visible wavelengths
What Happens to Incoming Radiation? Heat wavelengths
Imagine a hot and sunny summer day. You hold you hand up to the sun. What do you feel and why? Would you wear white or black? Why?
The ‘Real’ Greenhouse Effect
The ‘Real’ Greenhouse Effect
Solar Radiation passes in through glass. Radiation hits interior surfaces (ground and benches) and is transformed into longer wave heat. Heat radiates back outwards. Glass readily allow visible light to pass through (in/out) but serves as a partial barrier to heat waves passing through, which bounce back into the interior of the structure – warming it. Heat is retained inside the greenhouse largely because the structure reduces convective loss, thus preventing heated air from ‘blowing away.’ This is how ‘passive solar’ homes work – it’s visible radiation passing through glass, being transformed and being retained by heat mass structures (floors/walls) to re-radiate back later.
The Atmospheric “Greenhouse Effect" Earth Incoming Visible light Transformed Infra-red = heat Some infra-red is absorbed by atmospheric gases Remainder escapes into space
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