Vertical Cyclone Structure AOS 101 - Section 302 Ross A. Lazear May 1, 2007
Observations and Station Models AOS 101 Discussion Sections 302 and 303 .
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Transcript of Observations and Station Models AOS 101 Discussion Sections 302 and 303 .
Observations and Station Models
AOS 101 Discussion Sections 302 and 303
www.westcoastweathervanes.com
Observations What do we mean by observations?
Collecting data through various instruments
Importance of observations Assess current state of atmosphere Also aid in predicting future weather
Can be taken by people or automated sensors Examples
Buoys Ships Commercial aircraft (ACARS) Satellites www3.sympatico.ca
noaanews.noaa.gov
Types of Observations
Air temperature Dew point
temperature Air pressure Humidity Wind speed and
direction Cloud cover Ocean salinity Etc…
farm4.static.flickr.com
Air Temperature Air temperature is measured by a
thermometer
www.faqs.org
www.freefoto.com
www.weatherconnect.com
Dew Point Temperature
Dew point temperature 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
www.earlywomenmasters.net
www.edupic.net
Wet Bulb Temperature Measured with a thermometer
that has a moist cloth over the glass bulb The wet-bulb temperature is
reached when the air temperature is high enough to evaporate the water from the cloth
A simpler way to think of it The temperature you feel when
your arm is exposed to moving air
Can also be measured by a psychrometer
www.labsafety.com
Pressure
Units Hectopascals (hPa) Millibars (mb) Inches of mercury (inHg)
Why is pressure important? 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 Wind speed is measured by an anemometer
Weather vanes and wind socks tells us wind direction
www.greensvanes.co.uk
www.sportys.com
www.bom.gov.au
Air Pollution The concentration of pollutants can be
measured by an aerosol monitor
windows2universe.org
blog.lib.umn.edu
www.industrysearch.com.au
Heat Index The “apparent temperature”
How hot it really feels when relative humidity is taken into account with air temperature
Wind Chill
A description of “coldness” The discomfort
or danger resulting from wind and air temperature
Values found by calculation
Radiosonde A balloon-borne instrument platform
that transmitts its observations via radio Radio – radio transmitter Sonde – messenger in Old English
What does it measure? 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
Thermistor (Temperature) Hygristor (Humidity)
Can be used to find dew point Aneroid Barometer
(Pressure) Can be used to detect
different atmospheric layers Radio Transmitter & GPS Balloon & Parachute
Radiosondes cost approximately $300 and most of the time the instruments are never found
artemis.rsmas.miami.edu
www.plymouth.edu
Sounding Diagramrap.ucar.edu
Main Cloud Name Elements Alto
High Cirrus
Thin and wispy
Cumulus Fluffy
Nimbus Raincloud
Stratus Layer or
spread-out
Low-Level Clouds (~5,000 ft) Stratus
Form in low horizontal layers having a frayed or uniform base
Stratocumulus Puffy clouds that form following a cold front Can produce light rain
www.colby.edu
Stratus
upload.wikimedia.org
Stratocumulus
Low-Level to Mid-Level Clouds Cumulus
Fair weather clouds, fluffy From below ~6,500 ft to ~10,000 ft
Nimbostratus Constant precipitation and low visibility Above ~6,500 ft
upload.wikimedia.org
Cumulus
www.maltaweather.info
Nimbostratus
Mid-Level Clouds (~15,000 ft) Altostratus
Occurs when a when an air mass is lifted to the point where it condenses
Usually produces rain or snow Altocumulus
Formed by mid-level convective instability
Altostratus
www.victoriaweather.ca
Altocumulus
upload.wikimedia.org
High-Level Clouds Cirrostratus
Occurs when moist air cools to saturation at a high altitude
Made of ice crystals Cirrocumulus
Same as cirrostratus, but has convective instability
Cirrus Happens at the highest
part of the tropopause Usually means a storm is
approaching
mw2.google.com
Cirrostratus
upload.wikimedia.org
Cirrocumulus
upload.wikimedia.org
Cirrus
Vertically Developed Clouds Cumulonimbus
Develop from cumulus when the air mass is highly unstable
Usually forms thunderstorms
upload.wikimedia.org
Cumulonimbus
Aerosol Clouds Nacreous Clouds
Also known as “Mother of Pearl” Clouds
Made of sulfuric acid (H2SO4) drops
Formed in the stratosphere
Noctilucent Clouds Glows at night, observed as
waves Made of parts of meteorites Formed in the mesosphere
www.sflorg.com Nacreous
Clouds
Noctilucent Clouds
web.me.com
Station Observation Maps Surface observation map
http://aos.wisc.edu/weather/wx_obs/Surface.html Flash animation
http://www.rap.ucar.edu/weather/surface/displaySfc.php?region=cod&endDate=20110123&endTime=-1&duration=24
Station Observations
Air Temperature
Dew Point Temperature
Current Weather
Cloud Cover
Pressure
Wind Speed & Direction
• 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: 64 °F• Dew Point: 58 °F• Current Weather: Thin Fog
Most scientists measure temperature (T) in Celsius (°C) or Kelvin (K)
Temperature
Current Weather
Cloud Cover
Pressure If less than 500
Place 10 on the left and divide by 10 Examples
027 becomes 1002.7 mb 184 becomes 1018.4 mb
If greater than 500 Place 9 on the left and divide by 10 Examples
867 becomes 986.7 mb 642 becomes 964.2 mb
Wind Speed & Direction 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 Online Examples
Example 1 Example 2 Example 3 Example 4 Example 5
In-class Examples