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TT - Temperature: In
the United States surface temperature is expressed in units of degrees
Fahrenheit. In most other countries of the world it is expressed in degrees
Celsius. |
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TdTd
- Dew point temperature: Expressed in the same units as temperature . |
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N - Cloud cover: Total
cloud amount represents the fraction of sky covered by cloud. |
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VV - Visibility: How
far we can see, expressed in units of miles. |
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dd - Wind direction:
The line drawn represents the direction from which the wind is blowing. |
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ff - Wind speed: The
barbs on the lines representing wind direction give us information on the
wind speed. Wind speed is measured in knots (1 knot =1.15 miles per hour).
One long barb equals 10 knots, a short barb 5 knots and a triangle represents
a wind speed of 50 knots. |
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ww - present weather
conditions: Symbols are used to convey information on the type of weather
that was observed when the observations were made. Your book lists
some of these symbols. A more extensive list does exist. |
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PPP - Surface Pressure
adjusted to sea level. The units are coded in mb. The leading 9 or
10 are dropped as is the decimal. So 234 represents a pressure of
1023.4 mb while 834 represents a pressure of 983.4 mb. |
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pp - Change in surface
pressure over the last three hours. The change in pressure is represented
by a value and a line that tells us how the pressure was changing. |