Transcript Station models and clouds - Atmospheric and Oceanic Sciences

www.westcoastweathervanes.com
Observations and Station Models
AOS 101 Discussion Sections 302 and 303
Observations
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What do we mean by observations?
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Importance of observations
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Collecting data through various instruments
Assess current state of atmosphere
Also aid in predicting future weather
Can be taken by people or automated
sensors
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Examples
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Buoys
Ships
Commercial aircraft (ACARS)
Satellites
www3.sympatico.ca
noaanews.noaa.gov
Types of Observations
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farm4.static.flickr.com
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Air temperature
Dew point temperature
Air pressure
Humidity
Wind speed and
direction
Cloud cover
Ocean salinity
Etc…
Air Temperature
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Air temperature is measured by a thermometer
www.freefoto.com
www.weatherconnect.com
www.faqs.org
Dew Point Temperature
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Dew point temperature
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www.earlywomenmasters.net
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www.edupic.net
The temperature at which water
precipitates out of the air
Can be measured by a
hygrometer
Can be calculated by using
observations from a wet bulb
thermometer or psychrometer
Wet Bulb Temperature
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Measured with a thermometer
that has a moist cloth over the
glass bulb
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A simpler way to think of it
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The wet-bulb temperature is reached
when the air temperature is high
enough to evaporate the water
from the cloth
The temperature you feel when
your arm is exposed to moving air
Can also be measured by a
psychrometer
www.labsafety.com
Pressure
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Units
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Hectopascals (hPa)
 Millibars (mb)
 Inches of mercury (inHg)
Why is pressure important?
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Low pressure systems indicate
cooler or stormy weather
High pressure systems indicate
warmer or drier weather
Measured by a barometer
www.navyleagueshipsstore.com
Wind Speed and Direction
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Wind speed is measured by an anemometer
www.bom.gov.au
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Weather vanes and wind socks tells us wind direction
www.greensvanes.co.uk
www.sportys.com
Air Pollution
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The concentration of pollutants can be measured by an
aerosol monitor
blog.lib.umn.edu
www.industrysearch.com.au
windows2universe.org
Heat Index
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The “apparent temperature”
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How hot it really feels when relative humidity is taken into
account with air temperature
Wind Chill
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A description of
“coldness”
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The discomfort or
danger resulting
from wind and air
temperature
Values found by
calculation
Radiosonde
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A balloon-borne instrument platform that
transmitts its observations via radio
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What does it measure?
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Radio – radio transmitter
Sonde – messenger in Old English
Air Temperature
Pressure
Humidity
Wind Speed (indirectly)
It reaches a height of ~30km and at that height
the balloon swells to a 30 foot diameter!
www.ucar.edu
Radiosonde Instrumentation
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Thermistor (Temperature)
Hygristor (Humidity)
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Aneroid Barometer (Pressure)
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www.plymouth.edu
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Can be used to detect different
atmospheric layers
Radio Transmitter & GPS
Balloon & Parachute
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artemis.rsmas.miami.edu
Can be used to find dew point
Radiosondes cost approximately
$300 and most of the time the
instruments are never found
Sounding Diagram
rap.ucar.edu
Main Cloud Name Elements
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Alto
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Cirrus
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Fluffy
Nimbus
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Thin and wispy
Cumulus
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High
Raincloud
Stratus
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Layer or spreadout
Low-Level Clouds (~5,000 ft)
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Stratus
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Form in low horizontal layers having a frayed or uniform base
Stratocumulus
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Puffy clouds that form following a cold front
Can produce light rain
www.colby.edu
upload.wikimedia.org
Stratus
Stratocumulus
Low-Level to Mid-Level Clouds
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Cumulus
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Fair weather clouds, fluffy
From below ~6,500 ft to ~10,000 ft
Nimbostratus
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Constant precipitation and low visibility
Above ~6,500 ft
upload.wikimedia.org
Cumulus
www.maltaweather.info
Nimbostratus
Mid-Level Clouds (~15,000 ft)
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Altostratus
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Occurs when a when an air mass is lifted to the point where it
condenses
Usually produces rain or snow
Altocumulus
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Formed by mid-level convective instability
www.victoriaweather.ca
Altostratus
upload.wikimedia.org
Altocumulus
High-Level Clouds
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Cirrostratus
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Occurs when moist air cools to
saturation at a high altitude
Made of ice crystals
Cirrocumulus
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Cirrostratus
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mw2.google.com
Same as cirrostratus, but has
convective instability
Cirrus
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Cirrocumulus
Happens at the highest part of
the tropopause
Usually means a storm is
approaching
upload.wikimedia.org
upload.wikimedia.org
Cirrus
Vertically Developed Clouds
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Cumulonimbus
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Develop from cumulus when the air mass is highly unstable
Usually forms thunderstorms
upload.wikimedia.org
Cumulonimbus
Aerosol Clouds
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Nacreous Clouds
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Also known as “Mother of Pearl”
Clouds
Made of sulfuric acid (H2SO4) drops
Formed in the stratosphere
www.sflorg.com
Nacreous Clouds
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Noctilucent Clouds
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Glows at night, observed as waves
Made of parts of meteorites
Formed in the mesosphere
web.me.com
Noctilucent Clouds
Station Observation Maps
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Surface observation map
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http://aos.wisc.edu/weather/wx_obs/Surface.html
Flash animation
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http://www.rap.ucar.edu/weather/surface/displaySfc.php?region
=cod&endDate=20110123&endTime=-1&duration=24
Station Observations
Cloud Cover
Air Temperature
Pressure
Current Weather
Dew Point Temperature
Wind Speed & Direction
• Temperature: 64 °F
• Dew Point: 58 °F
• Current Weather: Thin Fog
• Cloud Cover: 75% Cloud Coverage - Broken
• Pressure: 1002.7 mb
• Wind Speed: 15 Knots (~7.5 m/s)
• Wind Direction: Out of the South-East (Northwestward)
Temperature
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Most scientists measure temperature (T) in Celsius (°C)
or Kelvin (K)
Current Weather
Cloud Cover
Pressure
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If less than 500
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Place 10 on the left and divide by 10
Examples
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027 becomes 1002.7 mb
184 becomes 1018.4 mb
If greater than 500
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Place 9 on the left and divide by 10
Examples
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867 becomes 986.7 mb
642 becomes 964.2 mb
Wind Speed & Direction
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Wind direction points in the direction that the wind is
coming from (Ex: out of the SE)
• 1 knot = 1.151 mph
• 1 knot = 0.514 m/s
Practice
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Online Examples
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Example 1
Example 2
Example 3
Example 4
Example 5
In-class Examples