What is meteorology??

1
What is meteorology??
(and why should you care?)
2
meteorologyThe study of the physics, chemistry,
and dynamics of the earth's atmosphere.
The American Meteorological Society defines a
meteorologist as a person with specialized
education "who uses scientific principles to
explain, understand, observe, or forecast the
earth's atmospheric phenomena and/or how the
atmosphere affects the earth and life on the
planet."
3
What do we mean by severe and unusual weather
extremes?
4
Severe weather not only includes things like
heavy thunderstorms, lightning, hail, flash
floods, and tornadoes. . .
5
. . . but all kinds of hazardous weather
6
In addition to the day to day weather, some
meteorologists study longer-term events like El
Niño, the ozone hole, acid rain, and global
warming
7
Some meteorologists study how dust from Africa
can be deposited in Florida, or how changes on
the Sun affect our atmosphere. Meteorologists
study how destruction of rain forests or
eruptions of volcanoes can change the composition
of our atmosphere.
8
Europes main threats flooding and heat
9
Extreme weather events are very costly. And have
been increasing recently.
10
The first thing we need to know is what the
atmosphere is made of
Percent composition of dry atmosphere, by volume Percent composition of dry atmosphere, by volume
ppmv parts per million by volume ppmv parts per million by volume
Gas Volume
Nitrogen (N2) 78.084
Oxygen (O2) 20.946
Argon (Ar) 0.9340
Carbon dioxide (CO2) 365 ppmv
In other words, more than 98 of the atmosphere
is nitrogen and oxygen Water vapor, not
displayed in this dry atmosphere chart, can
occupy anywhere from 0 4 volume, making it
the most variable atmospheric constituent
11
Amount of carbon dioxide in the atmosphere has
changed over time

• CO2 acts as a greenhouse gas
• As heat rises from earth surface, CO2 molecule
  absorbs it prevents from escaping to space
• Net result global warming
• Impt. caveat global warming is WAY more
  complicated than simply looking at chg of CO2
  over time
• At Mauna Loa, CO2 increased in the last 40 yrs,
  coincident with avg. sfc. temp of earth
  increasing 1C

12

13

• The relative composition varies from place to
  place on the surface of the Earth. The reason for
  this variation is the presence of aerosols and
  water vapor - both of which vary widely in
  amount
• Aerosols either tiny liquid droplets, such as
  fog, or tiny solid particles, such as ice
  crystals, smoke, sea salt crystals, dust, and
  volcanic emissions, suspended in the air.
• Aerosols play very important roles in cloud
  formation more on that later!

14

• Earths atmosphere probably had a very different
  composition when the planet first formed
• the earliest atmosphere may have had a
  significant amount of hydrogen and helium
• these gases were probably lost to space early in
  Earth's history because Earth's gravity is not
  strong enough to hold lighter gases
• a secondary atmosphere probably formed from
  gases being emitted by volcanoes
• the gases produced were probably similar to
  those created by modern volcanoes (H2O, CO2, SO2,
  CO, N2, ) and NH3 (ammonia) and CH4 (methane)
• there was essentially no free O2 at this time
  (not found in volcanic gases)

15
The vast amounts of water vapor expelled by the
volcanic earth resulted in the formation of
clouds which, in turn, produced rain. Over a
period of thousands of years, the rain
accumulated as rivers and lake and ocean basins.
The water reservoirs acted as sinks
for the large amounts of carbon dioxide (as they
do today) and through chemical and biological
processes became locked up in sedimentary rocks
as limestone.
The nitrogen, which is not very chemically active
continued to accumulate in the atmosphere.
16
While oxygen currently makes up about 21 percent
of the atmosphere, there was only a trace in the
air when life first appeared on the planet.
Oxygen first appeared in the environment when
early bacteria developed the ability to split
water molecules apart by harnessing the energy of
sunlight - a key part of photosynthesis.
Photosynthesizing organisms produced the oxygen
that accumulated over geologic time.
17
Next we need to know a little about the general
structure of the atmosphere. Start with
pressure.
18

• Consider a column of air 1 inch2 in size
  extending from sea level to the top of the
  atmosphere
• The weight (mass X gravity) of the column of air
  will be about 14.7 lbs
• Hence, the pressure at sea level is force/area
  14.7 lbs/inch2
• Sea-level pressure is also given in other units
• 14.7 lbs/inch2
• 1013.25 millibars
• 1013.25 hPa (hecto Pascals)
• 29.92 inches of Hg (mercury)

19
Atmospheric pressure decreases exponentially with
height. 50 of earths air lies in the lowest 6
kilometers (3.7 miles) Atmosphere officially
extends up over 100 miles
20
Pressure is basically the weight of the air
above a location so if youre location is sea
level, you have the greatest atmospheric
pressure. Pressure decreases exponentially with
height (more air molecules are found in air at
the surface than in the same volume of air aloft)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
Short clip about meteorologists, weather men,
hurricanes, and climate change
29
Atmosphere divided into different
levels Meteorologists concern ourselves with the
TROPOSPHERE Why?? Definition TEMPERATURE
INVERSION a layer of the atmosphere where the
temperature increases with height Rule of thumb
the word pause indicates the top of a layer.
Ozone is concentrated in the stratosphere
30
At the top of the troposphere is the tropopause,
which marks the beginning of the temp. inversion
of the stratosphere Thus the tropopause acts as a
good level for the top of buoyant clouds Note
that thunderstorm clouds are tallest in the
tropics
31
(No Transcript)
32
(No Transcript)
33
Interesting electromagnetic property of the
atmosphere at night ionosphere has different
properties than during the day. Thus, short-wave
radio waves (the AM frequency) can be reflected
and travel long distances from America to Europe
34

• We need to keep in mind a few simple rules
• Warm air is less dense (lighter) than cold air
• Humid air is less dense than dry air
• Less dense air can be forced up over denser air
• As air is forced upward, it cools and can form
  clouds and precipitation (if there is enough
  water vapor)
• The type of precipitation that falls will depend
  on the temperature of the air and the ground

35
(No Transcript)
36
In addition to forecasting the daily weather,
some meteorologists study severe weather, and try
to predict where it will occur
37
Meteorologists also study the past climate of our
planet from the most recent ice age (about
12,000 years ago), to dinosaur extinction (65
million years ago), to a time when our planet
might have been completely frozen (700 million
years ago), and even back to the beginning of our
planet
38
Some meteorologists also work to be able to
better predict what our planet will be like in
the future by studying the past
OR
39
In short, meteorologists study the Earth system
in an effort to help us better understand our
planet, for both the short and long time-scales.
40
A few definitions we need to know Temperature
measure of hotness or coolness of the air.
Specifically a measure of the kinetic energy of
an air molecule Pressure the force of air above
an area (remember, mass x gravity) Humidity
measure of amount of water vapor in the air