La Crosse Technology WS-2308AL Operation Manual page 17

Weather forecasting (LCD Section 2)
The three weather icons Sunny, Cloudy and Rainy represent the
weather forecasting. There are also two weather tendency indicators
to show the air pressure tendency either side of the weather icons.
Sunny Cloudy Rainy
Notes to inHg sensitivity setting for weather forecasting:
The inHg pressure sensitivity can be set to suit the user's requirement
for weather forecasting from 6 inHg, 9 inHg to 12 inHg (see Basic
Programming below). For areas that experience frequent changes
in air pressure (which does not necessarily reflect a change in the
weather) requires a higher inHg setting compared to an area where
the air pressure is stagnant. For example if 6 inHg is selected, then
there must be a fall or rise in air pressure of at least 6 inHg before the
weather station will register this as a change in weather.
Air Pressure (LCD Section 2)
The air pressure reading is displayed here. Press the PRESSURE
key to toggle between relative and absolute air pressure displays.
Notes to Absolute and Relative Air Pressure:
Absolute air pressure provides the display of the true measured air
pressure of the current time and location. This is not programmable
and the absolute air pressure range of the weather station is from
8.85 inHg to 32.45 inHg (standard air pressure at an altitude of
30,000ft is around 8.85 inHg).
Relative air pressure is the one value that is calculated back to sea
level from the local absolute air pressure and can thus be taken as a
reference for weather condition and weather development for the
entire country. It can be programmed to represent your local
surroundings. Since the relative air pressure is also the one value
given by various newspapers, TV and radio broadcasting stations in
their daily weather forecasts for their respective locations, users can
set the relative air pressure of the weather station to this value to
represent readings your their area (see Basic Programming Modes
below).
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