Every day, the weather impacts our lives and livelihoods in ways
both big and small......
Every day, the weather impacts our lives and livelihoods in ways
both big and small......
Every day, the weather impacts our lives and livelihoods in ways
both big and small......
Every day, the weather impacts our lives and livelihoods in ways
both big and small......
Every day, the weather impacts our lives and livelihoods in ways
both big and small......
From a purely economic standpoint, it's estimated that
weather variability can lead to as much as a 3 to 4%
change in US GDP in a given year......or in absolute terms,
as much as $500 billion per year.
Baseline: the mildest year of the past 20 years
Relative
impact
=
Worst weather
year
-
Baseline
case
Some of the US economic sectors most influenced by weather
(with % weather-induced variability) include:
Sector
% impact
Absolute impact
Mining
14.4%
$23.2 billion
Agriculture
12%
$24.4 billion
Manufacturing
8.2%
$197 billion
Finance, Insurance, Real Estate
8.1%
$210 billion
Utilities and Energy Production
7%
$23.6 billion
Construction
4.7%
$28 billion
Communications
4.7%
$17.6 billion
Transportation
3.5%
$15.5 billion
Weather is also a
significant cause of
mortality (although in
relative terms the
numbers are modest)
Deaths per million
population annually
Weather-related deaths broken down by cause.....
Key:
flooding (top)
lightning (middle)
tornado (bottom)
…..and geographically (deaths per million population annually)
Of course, weather also leads to significant property damage.....
Number of billion dollar weather events from 1980 to 2004
…..over $10 billion damage per year (on average)!
What is the atmosphere?
●
“A delicate life-giving blanket of air surrounding the Earth”
What is the atmosphere?
●
●
“A delicate life-giving blanket of air surrounding the Earth”
More precisely: a relatively thin layer of gases
consisting mainly of N2 and O2
- Dry air is roughly 78% N2 and 21% O2
- Water vapor varies, but can be up to 4% under
very humid conditions
●
The atmosphere is thin: 99% of the atmosphere by
mass is below 30 km in height!
What is the atmosphere?
●
●
“A delicate life-giving blanket of air surrounding the Earth”
More precisely: a relatively thin layer of gases
consisting mainly of N2 and O2
- Dry air is roughly 78% N2 and 21% O2
- Water vapor varies, but can be up to 4% under
very humid conditions
●
The atmosphere is thin: 99% of the atmosphere by
mass is below 30 km in height!
- For comparison, radius of the earth is 6400 km
Composition of the Atmosphere by Volume
Stuff that doesn't change
●
●
Stuff that varies or changes
Dry atmosphere is mainly N2 and O2
Water vapor is the main variable constituent (up to 4%),
followed by CO2
Water Vapor and Carbon Dioxide
●
●
●
●
Two important variable constituents are water vapor
and carbon dioxide
Evaporation of water at the ground / ocean surface
and condensation in clouds plays an important role
in the Earth's heat budget
Both are important greenhouse gases, meaning that
they trap heat energy radiated by the earth's surface
For both constituents, the concentration depends on a
competition between sources and sinks......
Sources and Sinks
of CO2
●
●
For most atmospheric
constituents, the
concentration depends
on a balance between
sources and sinks
The rate of creation /
destruction is measured
by the residence
timescale, or the time
to completely remove
the stuff if we were to
somehow shut off the
sources
Sources and Sinks
of CO2
●
●
For most atmospheric
constituents, the
concentration depends
on a balance between
sources and sinks
The rate of creation /
destruction is measured
by the residence
timescale, or the time
to completely remove
the stuff if we were to
somehow shut off the
sources
Residence timescales:
Carbon dioxide: 150 years
Water vapor: 10 days
Looking (Way) Ahead: CO2 Changes Over Time
●
Currently the sources of CO2 outweigh the sinks
Measurements at Mauna Loa
observatory, Hawaii
Looking (Way) Ahead: CO2 Changes Over Time
Mauna Loa measurements combined
with ice core record
Other Players
●
●
●
Ozone lives a double life in the atmosphere:
– In the stratosphere, it absorbs UV radiation, shielding life
at the Earth's surface
– Near the ground, ozone acts as a pollutant
Chlorofluorocarbons catalyze ozone destruction in the
stratosphere
– Responsible for the ozone holes that form each spring
Particulate matter (aerosols) and other chemicals act as
pollutants at the ground
A Sea of Air
A few quick facts:
●
●
A cube of air 1 mm on a side near the ground has roughly
1016 (or 10 million billion) molecules of air
On average, an air molecule at the ground moves less than
10-8 m (or one millionth of a cm) before colliding with
another air molecule
So even though we don't see it, we really are swimming in a
sea of air. The only reason we don't notice is that we're
adapted to this environment.