Weather
and
Climate
Atomosphere
• ~ 78% N2, 21% O2, and other trace gases
• composed of many layers
• the ozone layer (O3)which absorbs much of
the sun’s dangerous UV radiation
Atmospheric Pressure
• the pressure that results from the
column of air above us
• at sea level the air above you exerts a
pressure of 10.1 N/cm2
– this is about one ton of weight on (and all
around) your body!
• a barometer is a
machine that
measures how much
pressure the air is
pushing down with
• a rise in pressure
usually means
improving weather
while falling pressure
usually means bad
weather
Wind
• air moves from an area of high pressure
to low pressure
– this is down a pressure gradient that
results in wind
• the Coriolis effect explains how the
direction of the wind is influenced by
the Earth’s rotation.
– the earth moves faster at the equator than
at the poles
http://www.classzone.com/books/earth_science/terc/content/visualizations
/es1904/es1904page01.cfm?chapter_no=visualization
• In the Northern
Hemisphere winds move
clockwise
• in the Southern
Hemisphere, winds move
counter clockwise
The greenhouse effect
Warming/Cooling Trends
– scientists analyze tiny air bubbles trapped in
ice cores to learn about past:
• atmospheric CO2 concentration has increased
over 25% over the last few centuries
• this increase correlates with increase of Earth’s
temperature
Siple Station, Antarctica
75°55' S, 83°55' W
• a natural phenomena- over the past 900,000
years, the troposphere has experienced
prolonged periods of global cooling and
global warming.
• simultaneous warming on Earth and Mars
suggests that our planet's recent climate
changes have a natural-- and not a humaninduced cause
Cause
• energy passes through the atmosphere and is then
re-radiated by the surface as electromagnetic
radiation of a longer wavelength (now infrared)
than that of the original, incident radiation.
• water, CO2, oxides of nitrogen, and methane trap
infrared radiation causing global warming
• https://www.youtube.com/watch?v=cjuGCJ
JUGsg
Consequences of the greenhouse effect
• global temperature has ↑ by several degrees over
past decade, glacial deposits have melted across
the globe, and the recent thinning of Arctic and
Antarctic ice packs
• may cause melting of glaciers, flooding of lowlands, more frequent storms resulting in...
– decreased habitat
– increase in pest species (pathogens,
mosquitoes)
– dozens of amphibians’ extinction are
correlated with global warming
• Between 1979 and 2005, average Arctic sea ice
dropped 20% (as shown in blue hues).
• in order to reduce the greenhouse effect-- CO2
absorption by photosynthesis must go up and
emissions from burning fossil fuels must go down.
The Precautionary Principle
• "an ounce of prevention is worth a pound of cure",
"better safe than sorry", and "look before you leap".
• must prove that a human-induced change will not do
harm vs. it will do harm
• when an activity raises threats of harm to human
health or the environment, precautionary measures
should be taken even if some cause and effect
relationships are not fully established scientifically; in
this context the proponent of an activity, rather than
the public, should bear the burden of proof
• a willingness to take action in advance of scientific
proof [or] evidence of the need for the proposed action
on the grounds that further delay will prove ultimately
most costly to society and nature, and, in the longer
term, selfish and unfair to future generations."
Justification for Action?
• The economic harm of measures taken
now to limit global warming could
outweigh the potentially much greater
harm for future generations of taking
no action now
• Is it ethical to knowingly jeopardize
future human generations and damage
the habitat (possibly leading to
extinction) of other species?