La Crosse Technology WS-2315CH Operation Manual page 9

Weather forecasting (LCD Section 1)
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
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 1)
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).
Weather Data (LCD Section 2)
Indoor temperature and humidity are displayed simultaneously in this section.
Use the DISPLAY key to toggle through the displays for other weather
information:
- Outdoor temperature/humidity
- Outdoor wind chill
- Outdoor dew point
- Rainfall 24h
Rainy
- Rainfall 1h
- Rainfall total.
Notes to Dewpoint and Windchill:
Air can at a certain temperature only carry a certain amount of water (water
vapor), which also increases and decreases with temperature. If the air
temperature decreases below the dewpoint (saturation point), the excessive
water vapor will condense and fall out in form of dew, fog or rain. At a
temperature of e.g. 59°F and a relative humidity of 50% the dewpoint will be
about 41°F, at 80% humidity about 53.6°F. At a relative humidity of 100%
saturation is reached, i.e. the dewpoint is 59°F. At a dewpoint below freezing
the fallout will become frost or snow.
Windchill has been introduced for battle planning during World War II. It
represents not the real measured but the temperature a person feels in open
area under the influence of wind and cold. Windchill is laid out in tables for
various temperatures and wind speeds. At an outdoor temperature of e.g.
46.4°F and calm winds a person moving at a speed of 13 mph will already feel
a windchill temperature of 32°F.
Wind Data (LCD Section 3)
The current wind direction will be displayed on the LCD compass on the wind
section. Press the WIND key to toggle between wind direction as numerical
(e.g. 225°) and abbreviated characters (e.g. SW) as well as numerical wind
speed display inside the compass circle.