Kestrel 4000 Instruction Manual page 7

Kestrel 4000 Pocket Weather Tracker
® ®
Altimeter Setting
An aviation term for the local barometric pressure. Same as reference pressure.
Altitude
The distance above sea level. The Kestrel Meter calculates altitude based on the measured station pressure
and the input barometric pressure - or "reference pressure".
Barometric Pressure
The air pressure of your location reduced to sea level. Pressure will change as weather systems move into
your location. Falling pressure indicates the arrival of a low pressure system and expected precipitation or
storm conditions. Steady or rising pressure indicates clear weather. A correct altitude must be input for the
Kestrel Meter to display barometric pressure correctly.
Density Altitude
The altitude at which you would be, given the current air density. Often used by pilots in order to determine
how an aircraft will perform. Also of interest to individuals who tune high performance internal combustion
engines, such as racecar engines.
Dewpoint
The temperature to which air must be cooled in order for condensation to occur. The difference between
dewpoint and temperature is referred to as the "temperature/dew point spread". A low dewpoint spread
indicates high relative humidity, while a large dewpoint spread indicates dry conditions.
Heat Index
A practical measure of how hot the current combination of relative humidity and temperature feels to a
human body. Higher relative humidity makes it seem hotter because the body's ability to cool itself by
evaporating perspiration is reduced.
Kestrel 4000 Pocket Weather Tracker
® ®
DEFAULT SETTINGS
UNIT METRIC
Wind Functions M/s
Temperature Functions °C
Barometric Pressure hPa
Altitude Functions M
Time Format 24 hour
Date Format Day/month/year
SETTING FACTORY DEFAULT
Automatic Data Store On
Data Store Rate 1 hour
Data Overwrite On
Manual Data Store On
User Screen 1 Wind speed, temperature, humidity
User Screen 2 Humidity, dewpoint, wet bulb
User Screen 3 Pressure, altitude, density altitude
Display Contrast 10
Automatic Shutdown 15 minutes
Language English
PC Upload
Stored data may be uploaded to a PC with the optional Kestrel Interface.
IMPERIAL
mph
°F
inHg
Ft
12 hour
Month/day/year
Reference Pressure
The local barometric pressure. Input to the altitude screen to provide correct altitude readings. Also known
as the altimeter setting.
Relative Humidity
The amount of water vapor actually in the air divided by the maximum amount of water vapor the air could
hold at that temperature, expressed as a percentage.
Station Pressure
The air pressure of your location, NOT reduced to the sea level equivalent.
Temperature
The ambient air temperature.
Wet Bulb Temperature
The lowest temperature to which a thermometer can be cooled by evaporating water into the air at constant
pressure. This measurement is a holdover from the use of an instrument called a sling psychrometer. To
measure wet bulb temperature with a sling psychrometer, a thermometer with a wet cloth covering over
the bulb is spun rapidly through the air. If the relative humidity is high, there will be little evaporative
cooling and the wet bulb temperature will be quite close to the ambient temperature. Some exercise
physiology guides use wet bulb temperature, rather than heat index, as a measure of the safety of exercise in
hot and humid conditions.
Wind Chill
The cooling effect of combining wind and temperature. The wind chill gives a more accurate reading of
how cold it really feels to the human body. The Kestrel Meter's wind chill is based on the National Weather
Service standards as of November 1, 2001.
FREQUENTLY ASKED QUESTIONS
How do I set my Kestrel Meter to read the correct barometric pressure and altitude?
To measure these values accurately, you must know either your current pressure or altitude. If you know
the current barometric pressure, go to the altitude screen, and press the
pressure. As you adjust the reference pressure, you will notice that the altitude will change. Once the
reference pressure is entered, note the new altitude, and go to the barometric pressure screen. Press the
button to enter this altitude as the reference altitude. Your Kestrel Meter is now displaying the accurate
pressure and altitude. (If you start with a known altitude, simply start with entering this value as the
reference altitude on the barometric pressure screen. The adjust the reference barometric pressure on the
altitude screen.)
You will need to update the reference pressure and altitude as you change altitude or the weather changes.
For more information on this topic, see the Barometric Pressure and Altitude Adjustment section under
"Special Functions. "
Why is my Kestrel Meter is not registering wind speed?
It probably just needs a replacement impeller. You can verify this by removing the impeller (press firmly
on the sides of the impeller), and turn the unit on to the wind speed screen. Hold the Kestrel Meter near a
television, computer monitor or some electronic device and it will display a wind speed. Or, wave a magnet
(like a refrigerator magnet) back and forth by the Kestrel Meter. If the Kestrel Meter is working properly,
you will register a wind speed reading, even though there is no impeller installed. Simply purchase a new
impeller and your Kestrel Meter's wind speed readings will be restored to factory calibration.
What is the best way to take accurate temperature and humidity readings?
Avoid taking measurements in direct sunlight, and be sure there is airflow over the sensors. Especially if you
expose the Kestrel Meter to a large temperature swing prior to taking a reading (such as taking a Kestrel
Meter from the indoors to the outdoors in the winter), airflow over the sensors is necessary to measure
23
25
button to enter the reference