There is a lot of good weather information available on the Net. Most of it can be accessed without downloading a bunch of advertising and fluff. If you're serious about weather and value your time, this is the site!
 
Review the descriptions below to learn what's available. Once you're familiar with the sources, you can do all your navigating using the links on the left.
 
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 The Weather Underground still supports telnet at rainmaker.wunderground.com. If telnet is not your thing, they do have a website, but it's above ground and very commercial. The site has some good information, especially if you want an overview of another city, here or abroad. Try the form below to index directly into their site, (and try to ignore all the commercials):
 
    City:      State:                 

 

 

 

 

 


  Data, Terms and Conditions Index

Weather and aviation, like most sciences use a plethora of different terms and systems of measurement. The following topics will help you sort many of these out.

Millibars vs Altitude: A millibar is a unit of pressure where 1013.2 millibars are equivalent to the standard 29.92 inches of mercury used for mean sea level (MSL). Zero millibars represent a vacuum. The following table equates millibars with inches of mercury and matches those values to the average altitude they represent:

  Altitude  Millibars  Inches HG
    35,000      237.1        7.0
    18,000      504.6       14.9
    10,000      707.8       20.6
     5,000      843.2       24.9
       MSL     1013.2       29.9
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Fahrenheit vs Celsius: The Fahrenheit temperature scale, commonly used in the United States considers 32º the freezing point of water, and 212º it's boiling point (at mean sea level). Celsius uses zero degrees and 100º respectively. The formula to convert Fahrenheit to Celsius is (F-32)*5/9 = C. The following chart works fine for most conversions:

  Deg F    Deg C
    -30      -34
    -25      -32
    -20      -29
    -15      -26
    -10      -23
     -5      -21
      0      -18
      5      -15
     10      -12
     15       -9
     20       -7
     25       -4
     30       -1
     35        2
     40        4
     45        7
     50       10
     55       13
     60       16
     65       18
     70       21
     75       24
     80       27
     85       29
     90       32
     95       35
    100       38
    105       41
    110       43
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Metric, English and Nautical Measurements: Avaition and weather not only use both the English and metric systems for various measurements, but many distances and speeds are measured using Nautical miles. The following factors can be used for many common conversions. Multiply a unit on the left by the conversion factor to convert it to a unit on the right. Divide to move in the opposite direction:

  Unit             Factor      Unit
  In HG           33.8636      Millibars
  Liters             .264      U.S. Gallons
  Kilograms           2.2      Pounds
  Kilometers         .621      Statute Miles
  Statute Miles      .869      Nautical Miles
  Nautical Miles    1.853      Kilometers
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Lapse Rates: Air near the surface of the earth picks up heat from objects that have been warmed by the sun. Usually air close to the ground is warmer than air at higher altitudes. The average lapse rate (decrease in temperature) in the troposphere is about  2º C per 1000 feet  (3.6º F).

This should not be confused with the dry adiabatic lapse rate. When unsaturated air is raised and the pressure decreases, the air will cool. This air cools at about  3º C per 1000 feet  (5.4º F).

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Time Conversions: To avoid confusion, all aviation communications are conducted in English and time is referenced per the local time in Greenwich, England. This time is referred to as GMT, UTC, or Zulu during verbal communications. You'll often notice times supplied with weather products are referenced as GMT. The following chart will help you convert GMT to your local time:

                Add Hours to
  Time Zone     Obtain GMT
  EDT               4
  EST               5
  CDT               5
  CST               6
  MDT               6
  MST               7
  PDT               7
  PST               8
  AK & HI          10
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Phonetic Alphabet and Morse Code: To help pilots accurately communicate alphanumeric information the phonetic alphabet was devised. The following chart shows the word for each letter in the alphabet and the Morse Code representation:

  Alpha     .-        Sierra   ...
  Bravo     -...      Tango    -
  Charlie   -.-.      Uniform  ..-
  Delta     -..       Victor   ...-
  Echo      .         Whiskey  .--
  Foxtrot   ..-.      Xray     -..-
  Golf      --.       Yankee   -.--
  Hotel     ....      Zulu     --..
  India     ..        1        .----
  Juliett   .---      2        ..---
  Kilo      -.-       3        ...--
  Lima      .-..      4        ....-
  Mike      --        5        .....
  November  -.        6        -....
  Oscar     ---       7        --...
  Papa      .--.      8        ---..
  Quebec    --.-      9        ----.
  Romeo     .-.       0        -----
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