A gradual but steady rise indicates settled fair weather.
A gradual but steady fall indicates unsettled or wet weather.
A very slow rise from a low point is usually associated with high winds
and dry weather.
A rapid rise indicates clear weather with high winds.
A very slow fall from a high point is usually connected with wet and
unpleasant weather without much wind.
The following table of the United States Weather Bureau gives a summary
of the wind and barometer indications:
Barometer Reduced to Sea Level Wind Character of Weather Indicated
Direction
───────────────────────────────────────────────────────────────────────
30.10 to 30.20 and steady SW to NW Fair with slight temperature
changes for 1 to 2 days
30.10 to 30.20 and rising SW to NW Fair, followed within 2 days
rapidly by warmer and rain
30.10 to 30.20 and falling SW to NW Warmer, with rain in 24 to 36
slowly hours
30.10 to 30.20 and falling SW to NW Warmer, with rain in 18 to 24
rapidly hours
30.20 and above and stationary SW to NW Continued fair, with no
decided temperature change
30.20 and above and falling SW to NW Slowly rising temperature and
slowly fair for two days
30.10 to 30.20 and falling S to SE Rain within 24 hours
slowly
30.10 to 30.20 and falling S to SE Wind increasing in force, with
rapidly rain within 12 to 24 hours
30.10 to 30.20 and falling SE to NE Rain in 12 to 18 hours
slowly
30.10 to 30.20 and falling SE to NE Increasing wind, with rain
rapidly within 12 hours
30.10 and above and falling E to NE In summer, with light winds,
slowly rain may not fall for
several days. In winter,
rain within 24 hours
30.10 and above and falling E to NE In summer, rain probably
rapidly within 12 to 24 hours. In
winter, rain or snow, with
increasing wind will often
set in, when the barometer
begins to fall and the wind
sets in from the NE
30 or below and falling slowly SE to NE Rain will continue 1 or 2 days
30 or below and falling SE to NE Rain, with high wind, followed
rapidly within 24 hours by clearing
and cooler
30 or below and rising slowly S to SW Clearing within a few hours
and continued fair for
several days
29.80 or below and falling S to E Severe storm of wind and rain
rapidly or snow imminent, followed
within 24 hours by clearing
and colder
29.80 or below and falling E to N Severe northeast gales and
rapidly heavy rain or snow, followed
in winter by a cold wave
29.80 or below and rising Going to Clearing and colder
rapidly W
A sudden fall indicates a sudden shower or high winds, or both.
[Illustration:
_Courtesy Julien Friez & Son Baltimore, Md._
Fig. 49
U. S. STANDARD RAIN GAUGE
]
A stationary barometer indicates a continuance of existing weather
conditions. (_Note_: Tap the barometer slightly on the face. If the
hands move a trifle, it indicates that there is the tendency to rise or
fall, depending upon the direction of movement of the hands.)
Northeasterly winds precede storms that approach from the southwest;
that is, in New England and the Middle States and the Ohio Valley.
Southeasterly winds precede storms that approach from the Lake region.