Transcript Weather and Climate

Weather in
Troposphere
SHORT TERM PRESSURE , TEMPERATURE, MOISTURE
CONDITIONS IN THE ATMOSPHERE
REGENTS EARTH SCIENCE WITH MS. CONNERY
Weather and climate result from
temperature, pressure, and moisture
in Earth’s atmosphere
The external
energy source
that drives
Earth’s weather
and climate is…
INSOLATION
INCOMING SOLAR RADIATION
RADIATION is energy transfer by waves
CONDUCTION – energy transfer by direct molecule to
molecule interaction (contact).
Conductors (metals) do this well but insulators (air) don’t!
Less dense floats up and
takes energy with it
More dense sinks down
and heats up again
CONVECTION - Energy transfer by density
circulation. MOST IMPORTANT in
WEATHER and CLIMATE
To understand weather & climate you
need to know relations among:
 temperature (kinetic energy of air molecules)
 pressure (force related to air’s composition
and density)
 moisture (humidity in the atmosphere)
And their role in the water cycle locally and
around the globe!
WATER CYCLE results from
convection in the atmosphere
infiltration
Long-term latitude based
convection of water cycle cause
climate zones on Earth
Equator
http://www.cid.harvard.edu/ciddata/geog/GISfiles/kgzones_lrg.jpg
Warm and cold currents in ocean circulation
occur because of convection and effect climate
PHASE CHANGE
REVIEW!
GAS
PHASE CHANGE
REVIEW!
GAS
Temperature =
average kinetic
energy of the
molecules
Pressure = force exerted by the
molecules over an area. Related
to density and composition of air.
The range in air pressure typically
found on Earth is ~ 960-1040 mb
Weather and climate result from
temperature, pressure, and moisture
in Earth’s atmosphere
Relation between altitude, air pressure,
density, and gravity
Humidity measures
moisture in the air.
What’s in the atmosphere? (ESRT p1)?
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“Other”
Water vapor
Carbon
dioxide
Methane
Nitrous oxide
Water (H2O) as vapor is less
dense than nitrogen gas (N2)
or oxygen gas (O2) so moist
air masses rise in atmosphere
Humidity (moisture) changes the
density and pressure of an air mass.
What is the density relationship
between moist air and dry air?
Which one creates higher pressure if
it is more dense?
What’s in the atmosphere? (ESRT p1)?
Stratosphere has
ozone layer that
protects us from
harmful UV and
other short
wavelength
radiation
“Other” are
greenhouse gases
 Water vapor
 Carbon dioxide
 Methane
 Nitrous oxide
Greenhouse effect
is a general long
term warming of
the planet due to
heat trapping in the
atmosphere
What are greenhouse
gases and the
greenhouse effect?
Stratosphere has
ozone layer that
protects us from
harmful UV and
other short
wavelength
radiation
What’s the first thing
you think of when
someone says
weather around
here?
Cirrus = wispy ice clouds
Cumulus =
fluffy clouds
stratus clouds = extensive layers
NIMBUS CLOUDS =
PRECIPITATION OCCURRING
Cirro = high clouds
(>6 km high)
Cirrocumulus
Cirrostratus
Altocumulus
(ALTO = mid level of about 3-6 km
high)
Altocumulus
Altostratus
LOW CLOUDS <3 km HAVE NO
PREFIX
Cumulus
Fog
Fog
Cumulonimbus =
unstable storm clouds
Contrails = ice from plane
exhaust
MAJOR CLOUD TYPES
CLOUD HEIGHT PREFIXES
CIRRUS
CIRRO-
CUMULUS
ALTOSTRATUS
NIMBUS
NO PREFIX
CLOUD OBSERVATIONS
Why are clouds named this way?
Real World - Why does the size of an air mass
change as it rises?
Clouds form
when water
vapor (gas) in
air condenses
to liquid.
Clouds form
when the air
mass cools to
the dew point
temp!
How do we measure moisture
in the air?
Sling psychrometer
a tool to measure the relative humidity &
dew point temperature of the air
Dew Point and Relative
Humidity
Dry Bulb Temp
(oC)
Wet Bulb Temp
(oC)
Wet-bulb
Depression (oC)
Dew Point Temp
(oC)
Relative
Humidity (%)
1
2 - outside
classroom
oC
oC
oC
oC
3
4
5
20oC
4oC
28oC
12oC
-1oC
19oC
SLING PSYCHROMETER tool that measures
atmospheric moisture (humidity) & dew point
temp
Dry bulb  measures air temperature
Wet bulb  some wet cotton on a
thermometer that measure
temperature after evaporation occurs
What happens to the temps when you
swing it? Why?
Steps to determine relative
humidity and/or dew point temp
1. Wet the cotton on the wet bulb
2. Sling the psychrometer until the values stabilize over
two readings
3. Record the air temperature (dry bulb)
4. Record the wet bulb temp
5. Subtract (dry – wet temp) to find the wet bulb
depression
6. Use the proper ESRT tables to find dew point temp and
relative humidity
Evaporation cools the air because
the wet bulb temperature got
lower when the water evaporated
from the wet cloth
condensation heats up the air
because the energy is released from
the water vapor molecule into the
air as the water molecule cools
from gas to a liquid.
Reaching the dew point temp at higher
altitudes shows energy transfer by
convection – the water cycle!
CONVECTION in a room
There would be no weather
without convection
The external
energy source
that drives
Earth’s weather
and climate is…
INSOLATION
INCOMING SOLAR RADIATION
What can happen to light energy
(insolation) from the sun?
1. Absorbed – molecular capture of light
energy from the sun
2. Reflected – light energy bounces off
3. Reradiated – absorbed light energy is
converted from light  heat and
returned back to atmosphere in its new
form of infrared
Reference Table page 14
HEAT (INFRARED)
RERADIATED BACK TO
ATMOSPHERE and SPACE
LIGHT FROM
SUN!
Uneven heating and cooling of
earth’s surface drives convection!
Ways air masses lift to get
convection started
- air masses have characteristics based
on where they form at Earth’s surface
- air masses get forced up at fronts
- air masses get forced over mountains
Air masses take on the temperature
and moisture characteristics of the
places where they form
at high or low latitudes (temp)
over land or sea (moisture)
We already know that the
angle of insolation affects
temperature daily, seasonally,
and at each latitude)
Fronts are the leading edge of
air masses.
Fronts are where air is forced
over another air mass and cools
as the it rises up in altitude.
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That’s why there’s usually
precipitation at fronts!
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Symbols used to show fronts on
weather maps
Fronts are
boundaries
of air masses
with different
temperature
and moisture
conditions
A cold front advance is fast and furious – Think instability & BIG
STORMS like thunderstorms and supercells with Tornadoes
Warm front moves over cold
front
Occluded fronts : warm air mass
squished between cold air
masses
Occluded front
What happens
after a front
passes through
an area?
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Remember – the prevailing wind direction
drives the air mass forward
The new air mass controls conditions once
it arrives
Temperatures change to whatever that air
mass characteristics are
Clearer skies likely when high pressure
Generally less wind when high pressure
In this lab you
will use temp,
winds, & air
pressure to find
the front
boundaries and
predict weather.
Break the
Pressure code
Mid latitude cyclone: counter-clockwise
Prevailing winds move
storms along a typical path
Why do the radial storm arms rotate
around the low pressure system in a
cyclone pattern (counter-clockwise)
in the northern hemisphere?
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Coriolis Effect (curves because
of Earth’s rotation)
It’s same reason that the
prevailing winds curve to the
right in northern hemisphere,
too!
Coriolis
Effect
LAB 26 – CLIMATE
How the oceans, atmosphere, and land respond to sun’s energy and
moisture is what drives our weather & climate patterns on earth.
Equator
http://www.cid.harvard.edu/ciddata/geog/GISfiles/kgzones_lrg.jpg
Latitude based convection
affects climate
Prevailing wind direction
affects climate
Warm and cold currents ( ocean circulation) affect climate
Mountains affect
climate because
they force air up
and down
Forcing it over
a mountain!
PROPERTIES of MATERIALS on
EARTH affect climate because they
handle energy in different ways
SPECIFIC HEAT is the property of
a material that determines its
ability to absorb and reradiate
energy
LAND and SEA are a good place
to start
SPECIFIC
HEAT
Energy needed
to raise temp
of 1g of mass
by 1oC
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Land or sea? Which
changed temp
rapidly?
It took less energy
for the land to
change temperature.
Land is a good
absorber and
reradiator of energy.
It does not store
energy well.
That’s what low
specific heat means.
SPECIFIC
HEAT
Energy needed
to raise temp
of 1g of mass
by 1oC
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Sea changed temp
slowly.
It took more energy
for the sea to change
temperature.
Water is a poor
absorber and
reradiator of energy.
It stores energy
well.
That’s what high
specific heat means.
What does this material difference
in rate of heating and cooling cause?
What happens at the beach during the
day when the land absorbs energy faster
than the water?
What happens at the beach at night
when the land reradiates heat
faster than the water?
LAB 26 – CLIMATE
How the oceans, atmosphere, and land respond to sun’s energy and
moisture is what drives our weather & climate patterns on earth.