Understanding the measurements – Kestrel 3500 User Manual

Page 3

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Kestrel® 3500 Pocket Weather® Meter

5

5. Hold mode. While holding

MAX

AVG

, press

MAX

AVG

to hold the time and all of the measured values.

The word “HOLD” will blink to indicate the Hold Mode. Press

MAX

AVG

or

MAX

AVG

to view the other

measurements in Hold Mode. While holding

MAX

AVG

, press

MAX

AVG

to exit the Hold Mode. This

mode can be useful for taking measurements when unable to view the display.

6. Turn on the backlight. Press

MAX

AVG

to activate the backlight for 10 seconds. If

MAX

AVG

or

MAX

AVG

are pressed while the backlight is illuminated, the backlight will remain illuminated for

another 10 seconds. Press

MAX

AVG

while the backlight is illuminated to manually turn off the

backlight.

7. Adjust the clock. Simultaneously press

MAX

AVG

and

MAX

AVG

to adjust the clock. While the clock is

blinking, press

MAX

AVG

or

MAX

AVG

to adjust the clock. Hold

MAX

AVG

or

MAX

AVG

to adjust the times quickly.

Simultaneously press

MAX

AVG

and

MAX

AVG

to exit the clock adjustment.

8. Turn off. Hold

MAX

AVG

for 2 seconds to manually turn off the unit. The unit will automatically

turn off if no buttons have been pressed for 45 minutes.

UNDERSTANDING THE MEASUREMENTS

Wind Speed - average over the previous three seconds. The measurement will be accurate

for air flow through the front or rear of the unit.
Maximum Wind Gust - maximum 3 - second wind speed since the unit was turned on.
Average Wind Speed - average wind speed since the unit was turned on.
Temperature - instantaneous temperature of the thermistor, which is located at the end

of the long coiled leads in the open cavity below the impeller. The exposed thermistor will

respond quickly to changes in temperature when air flows past it. For fastest response, either

hold the unit into the wind or wave the unit side to side for 15 seconds. Readings should be

taken in the shade. Water and snow temperatures can be taken by hold the unit in the water

or snow.
Wind Chill - combination of wind speed and temperature, as defined by the US National

Weather Service. Wind chill is the effective temperature on a human or animal at low

temperatures due to wind speed. Wind chill readings will be the same as the temperature

readings above 45ºF or below 3 mph.
Relative Humidity - amount of moisture in the air compared to the amount of moisture the

air can hold for the given temperature, represented as a percent. Because relative humidity is

also a function of the temperature, the response time will be dependent on the temperature

response time (see temperature section above). Readings should be taken in the shade.
Heat Stress – combination of temperature and humidity, as defined by the US National

Weather Service. Heat stress is the effective temperature on a human or animal at high

temperatures due to humidity. Heat stress readings will be the same as the temperature

readings below 70ºF.
Dewpoint – calculated based on temperature and humidity measurements, as a measure of

moisture content in the air. If the dewpoint is very close to the temperature, the air is humid.

If the temperature and dewpoint are the same, dew will form. If this happens below freezing,

frost will form.
Wet Bulb Temperature - calculated based on temperature and humidity measurements, as a

measure of evaporation rate. If the wet bulb temperature is very close to the air temperature,

the air is humid. Wet bulb temperature is typically measured by swinging a mercury

thermometer with a wet sock on its end for several minutes.

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