Transcript The Atmosphere - Lamberth APES

Structure & Characteristics
Atmosphere: A thick blanket of gases
surrounding a planet
*composed of AIR
(a mixture of gases)
*
*Levels of oxygen
and other gases
decrease with
elevation until
there are too few
gas molecules to
detect.
*Temperatures may
also fluctuate with
changes in
elevation
*
Thermosphere
* Named the thermosphere because of
changes in temperature that rise with
altitude and interaction with the Sun
* During the day temperatures in this layer
of the atmosphere can increase by 200500 degrees Celsius
* This is also the layer where the auroras
may occur because of high energy
photons from the Sun exciting molecules
in the atmosphere
*
* Aurora Borealis Video
*Aurora video from the
International Space Station
*
Mesosphere
* Meso- means “middle”
* Temperatures decrease with height in
this layer and reach the coldest
temperatures in the atmosphere at the
top of the Mesosphere (-90o Celsius!)
* Most meteors burn up in this layer
*
Stratosphere
* Second layer of the atmosphere.
* This layer contains the ozone layer- a
concentration of O3 molecules that absorb
UV rays from the Sun and warm the
Earth.
* Because of the ozone layer the
temperatures in the Stratosphere
increase with height.
* This is also a layer where airplanes may
sometimes fly on long distance flights.
*
Troposphere
* The lowest layer of the atmosphere that
starts at the surface of the Earth.
* This is where most of the weather occurs
because most of the clouds are formed in
this layer.
* Temperatures in the troposphere
decrease with height as well as density of
air particles making it harder to breathe
the higher you climb.
*
Most of the changes we experience in the
atmosphere come from differences in temperature or
differences in air pressure.
Differences in
temperature come
from different
amounts of solar
radiation absorbed
by the atmosphere
and the surface of
the Earth.
*
*Radiant energy: energy that comes from the sun
50% of the Sun’s energy is
reflected or absorbed by the
atmosphere. This can vary
according to latitude.
*
* Solar energy is transferred through the atmosphere
through radiation.
Radiation: the transfer of energy in the form of waves
*
* When solar radiation is absorbed by the atmosphere or by
the surface then it can be measured in terms of heat or
temperature.
Heat: the form of energy that flows between two samples of
matter due to their difference in temperature
Temperature: average kinetic energy of the atoms or
molecules in a particular substance
*
Conduction: direct
transfer of energy from
one substance to
another
Convection: transfer of
energy in a fluid (warm
air rises, cool air sinks)
*
* Global convection is responsible for transferring heat
from different areas of the Earth through masses of air
or convection cells.
*
* Temperature can vary according to 3 things:
1)
Geographic Position
2)
Altitude
*
* Temperature can vary according to 3 things:
3) Surface Material
Thermometer: instrument
used for measuring
temperature
Isotherms: lines on a
weather map that connect
places with the same
temperature
*
*
* Water vapor is the most important ingredient in
cloud formation and changes in the weather.
Water in the atmosphere relies on
changes in temperature and heat energy
*
Humidity: amount of water vapor in the
atmosphere
Maximum saturation = as much water vapor as
the air can hold
*
* As temperature increases so does the amount of water the air
can hold.
Relative humidity: (present water vapor/ water vapor
when saturated) x 100
Specific humidity: actual moisture in the air
*
* A number of factors affect the humidity of the air. Pressure
and temperature can change the amount of moisture the air
can hold and have an effect on dew point.
Basic Trends
1) As temperature increases,
maximum saturation increases
 Maximum saturation = 100% relative
humidity
 100% relative humidity = dew point
*
Dew Point: the temperature at which the air becomes cool
enough for water vapor to condense into liquid water.
 high relative humidity indicates that the dew point is closer
to the current air temperature. Relative humidity of 100%
indicates the dew point is equal to the current temperature.
Psychrometer: instrument used
for measuring relative humidity
Hygrometer: instrument used for
measuring the specific humidity or
moisture in the air
*
*
* The result of the air reaching its dew point is the
condensation of water vapor into clouds.
Cloud: visible masses of tiny water and ice particles
suspended in the atmosphere
For a cloud to form you must
have:
-Water or moisture in the air
-Dust particles
-A change in temperature
and/or pressure
*Clouds are characterized
by their size, shape and
altitude.
*The 3 main groups of
clouds are:
1) Cumulus
2) Stratus
3) Cirrus
*
Fog: condensation that
forms clouds near the
Earth’s surface
*
- thin, feathery,
made of ice crystals
- form at high
altitudes
- seen when weather
is fair, but can mean
rain or snow
- “a curl of hair”
Cirrus Clouds
*
Stratus Clouds
-Low sheets or layers; gray and
smooth
-Block out the sun
-Associated with rain and drizzle
-“a layer”
*
Cumulus
Clouds
-Piled in thick, puffy masses
-Usually mean fair weather
-“a pile”
*
Cumulonimbus
Clouds
large cloud that produces
LIGHTNING, THUNDER,
HEAVY SHOWERS =
Thunderstorms
*
Nimbostratus
Rain Clouds
Stratocumulus
*
Cirrostratus
Cirrocumulus
*
Contrails
Mammatus
*
*
* Precipitation: any moisture that falls from the
atmosphere
* Occurs when condensation in the clouds
becomes too heavy and falls to the surface
* Starts when water vapor attaches to
condensation nuclei then becomes visible
*
Types of Precipitation
Drizzle: fine drops….less than 0.5mm diameter
Rain drops: larger… 0.5mm to 5mm diameter
Snow: falls in clumps of six-sided crystals
Sleet: pellets of ice that fall to the ground when
raindrops fall through freezing air
*
Types of Precipitation
Hail: lumps of ice
- comes from cumulonimbus clouds
- made of layers of ice
*
Formation of Hail
*
Extreme Weather
Lightning: a discharge of electricity from a
thundercloud to the ground, or cloud to cloud, or
ground to cloud
*
Extreme Weather
Lightning characteristics
• temperature inside lightning flash can reach 28,000°C
• at this temperature, air expands explosively and sudden
expansion makes thunder!
*
Extreme Weather
Tornado: a narrow, funnel-shaped column of spiral
winds that extends downward from the cloud base and
touches the ground
•strongest winds between 360
and 500 km/hr
•funnel less than 500 m across
•always travel with a parent
thunderstorm at speeds
ranging from 40 to 65 km/hr
*
Extreme Weather
Tornados usually occur during spring and summer and most
likely occur in late afternoon
*
Extreme Weather
Fujita Scale: scale used for categorizing tornadoes
by strength and damage
*
Extreme Weather
Hurricane: an intense tropical low-pressure area with
sustained winds starting at 75 mph
Hurricanes only form in warmer water temperatures and in other
parts of the world they can be called cyclones or typhoons
*
Extreme Weather
Parts of a Hurricane
Eye: central area of sinking air; 15 to 20 km wide
Eye wall: area of the
hurricane surrounding
the eye with the most
violent winds in the storm
*
Extreme Weather
Parts of a Hurricane
Storm surge: currents formed when hurricanes pile
water up along the shore and blow it inland
*
Extreme Weather
Movement of Air in a Hurricane
Hurricane winds and strength depend on
the updraft of warm air and water along
with downward pressure of colder air
*
Extreme Weather
Leading up to the storm
Tropical depression: wind speeds up
to 38 mph; some circular rotation at
surface
Tropical Storm: wind speeds from
39-74 mph; can be named, shows
drop in pressure, distinct rotation
*
Extreme Weather
Leading up to the storm
Hurricane watch: threat of
storm conditions within 2436 hours
Hurricane warning: due to
strike within 24 hours
*
Extreme Weather
Hurricane Ratings
Use the Saffir-Simpson
scale that rates
hurricanes based upon
their wind speed, storm
surge, and damage.
*