Kestrel® 2500 Pocket Weather® Meter
11
About the Backlight
The Kestrel 2500 NV has a night-vision preserving backlight which helps users to sustain
natural night vision. The NV’s backlight incorporates an optical
fi
lter to reduce overall
brightness and minimize blue and green spectrum light to preserve night vision.
Additionally, the backlight is much dimmer than a standard backlight, making it more
di
ffi
cult to detect with the naked eye in night operations. This backlight appears soft greyish
pink (not red) and is still in the visible spectrum, so it is not compatible with night-vision
equipment.
It takes 30 to 45 minutes for the average eye to adapt to darkness and maximize night
vision. Even a short burst of white, yellow, green or blue light “bleaches out” the rod cell
photoreceptors in the eye and causes night blindness until the entire adaptation process can
take place again. Light in the red spectrum does not cause this “bleaching out”, preventing
night blindness and night vision fatigue.
Sensor Calibration
All the sensors have been factory calibrated to be accurate within speci
fi
cations. For
recalibration, you may either return it to Nielsen-Kellerman for factory calibration, or contact
NK for
fi
eld calibration instructions.
BEAUFORT SCALE
The Beaufort Scale is a system for estimating wind force
without the use of instruments based on the visible e
ff
ects
of the wind on the physical environment. The behavior of
smoke, waves, trees, etc., is rated on a 13 point scale. The
scale was devised in 1805 by the British naval Commander
Sir Francis Beaufort (1774-1857) and is still commonly used
by mariners.
KESTREL POCKET WEATHER METERS
5-YEAR LIMITED WARRANTY
NK does not believe in “disposable electronics.” We know
that Kestrel Meters don’t typically lead pampered lives, and
we design them for years of performance in tough conditions. Every Kestrel is designed and
manufactured at NK’s facility in Boothwyn, Pennsylvania, to be the accurate, reliable weather
instrument you need for your application. If for any reason you are not satis
fi
ed with the
performance or operation of your Kestrel meter in the
fi
rst 30 days, you may return it to your
place of purchase for a full refund.
We guarantee every Kestrel Pocket Weather Meter to be free of defects in materials and
workmanship for a period of FIVE YEARS from
their date of
fi
rst consumer purchase.
NK
will repair or replace any defective product or part when noti
fi
ed within the warranty period,
Force Description
Kts
0
Calm
0
1
Light Air
1-3
2
Light Breeze
4-6
3
Gentle Breeze
7-10
4
Moderate Breeze 11-16
5
Fresh Breeze
17-21
6
Strong Breeze
22-27
7
Near Gale
28-33
8
Gale
34-40
9
Strong Gale
41-47
10
Storm
48-55
11
Violent Storm
56-63
12+
Hurricane
64+
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