Transcript WEATHER AND CLIMATE

WEATHER AND CLIMATE
WEATHER
• Refers to the conditions
in the atmosphere at a
given place and time
• Changes from hour to
hour and day to day
– Temperature
– Atmospheric (barometric)
pressure
– Precipitation
– Wind
– Humidity
– Cloudiness
WEATHER
• Results from interactions
between leading edges of
moving warm and cold air
masses called fronts
• Warm front—warm air
replacing cooler air
– Less dense air rising over
cold. Acts as a moisture
condenser forming clouds
– Clouds thicken, descend,
then rain
• Cold front—cold replacing
warm
– Stays close to ground
producing rapidly moving
towering clouds
(thunderheads)
WEATHER
• Also affected by changes in
atmospheric pressure
• Greater at surface
• High pressure—cool dense
air descends becoming
warmer. Generally, clear cool
weather
• Low pressure—low density,
air rises warmer air expands
and cools causing
condensation forming clouds.
Generally, cloudy stormy
weather
WEATHER
• Relative humidity—amt.
of water vapor in the air
compared to the max.
amt the air can hold at a
specific temp.
• Dew point—temp. at
which water vapor
saturates from an air
mass into liquid or solid.
Occurs at 100% humidity
CLIMATE
• Average weather conditions
that occur over a period of
years
• Changes slowly over
hundreds or thousands of
years
– Temperature—average and
extremes
– Precipitation—averages,
seasonal, distribution
– Also includes wind, humidity,
fog, cloud cover—seasonal and
yearly variations
CLIMATE
• Wladimir Köppen developed system for classifying
climates
– Divided into 6 zones—humid equatorial, humid temperate,
humid cold, dry, cold polar, and highland climate
CLIMATE CHANGE
• Measurements showed
CO2 levels went from
315 ppm in 1958 to 383
ppm in 2006
• Every May levels drop
slightly as plant growth
occurs but rises again in
the winter
CLIMATE CHANGE
• Surface temp increased
by .6⁰C over past cent
w/ most in past 2
decades
• Greenhouse gases have
increased
– CO2 by 31%
– CH4 by 151%
– N2O by 17%
AIR POLLUTION
• Not counting CO2 and soil
• Americans release 147
metric tons of air
pollution/yr. Worldwide 2
billion tons
• Air quality has improved
over past 20 yrs
• 1990 regulation of most
hazardous materials
began reducing emissions
by 1 million tons/yr
AIR POLLUTION
• Conventional
pollutants—7 major
pollutants
– SO2, CO, particulates,
NOx, ozone (O3), lead,
volatile organic
compounds (VOC’s)
– Ozone—released from by
combustion. Interacts
with UV radiation.
Affects lung function
SOURCES & PROBLEMS
• SO2—colorless corrosive
gas. Damages plants and
animals.
• NOx—highly reactive
gases formed by
combustion. Gives smog
its color part of acid rain
• CO—colorless and
odorless, highly toxic.
Inhibits respiration
SOURCES & PROBLEMS
• Particulates—dust, ash, soot,
lint, smoke, pollen. Leaves
residue damaging tissues
• VOC’s—organic gases from
plants, bogs, termites. Forms
photochemical oxidants and
makes ozone
• Lead &other toxic
elements—lead, mercury,
arsenic. Highly reactive
damaging nervous system
EFFECTS OF AIR POLLUTION
• Breathing polluted air
increases heart attacks,
respiratory disease and
lung cancer
• A 5-10 yr decrease in life
expectancy if you live in
highly polluted areas (LA &
Baltimore)
• Bronchitis & Emphysema
common conditions
– Accts for 50,000 deaths
EFFECTS OF AIR POLLUTION
• Plants are extremely
sensitive
• SO2 & sulfuric acid
destroys tissues
• Cell membranes
damaged
• Chlorophyll destroyed
• Metabolism, growth &
development disrupted
EFFECTS OF AIR POLLUTION
• Smog & haze reduces
visibility
– Without visibility would
reach 150 km (90 mi)
instead of the 15 km
(9mi) we are used to
• Acid Rain damages
plants, lowers pH,
destroys buildings &
monuments