Snow White®
Chilled mirror dew-point
hygrometer for radiosonde
Water vapour measurement in troposphere and
lower stratosphere
Recommended as working reference sensor
Low cost chilled mirror dew point sensor
Designed for radiosonde application
Light weight
Accurate measurement of dew-point or frost-point
Detects clouds and measures their liquid and solid
water content
The upper troposphere and lower stratosphere present the
greatest challenge to radiosonde relative humidity
measurements, because of the low temperature
involved, (down to -80 °C) , and because of the problems
of contamination of water vapor picked up on passing
through upper cloud.
The new yellow “hydropor” material reduces
contamination effect, and therefore the instrument is
useful at higher altitude than previous Snow White®
design.
Chilled Mirror:
Whereas all the operational radiosondes measure relative
humidity and are calibrated with respect to relative humidity,
the Snow White chilled mirror measures dewpoint or frost
point directly (depending on whether the film on the mirror
is water or ice) Main advantages of the chilled mirror system
over conventional systems are enhanced accuracy, and
higher measuring speed. Another advantage is the absence
of saturation effect.
Technical Data ….
Nominal operating altitude
0…~24 000m
Nominal operating time
max 4 hours
(Daytime version 0… ~12 000m)
Measurement range
2…100%rF
-40…20°C
Mirror temperature range
-80°C…+40°C
(Daytime version –60°C….+40°C)
Resolution
0.01°C, 0.1%rF
Accuracy
0.2°K / 2%rF
DewPoint / relative humdity
Reproducability in sounding
0.2°K / 2%rF
DewPoint / relative humidity, measured with double soundings
Max dew point depression @ 0°C
45K
Daytime version 40K
Max dew point depression @ -60°C
25K
Daytime version 20K
Response time
<0.5 s
5m/s, 0°C…+40°C, 500…1000hPa
Response time
<2s
5m/s, -60°C…0°C, 3…500hPa
Case material
Styrofoam “Hydropor”
Power Supply
9V/0.6Ah
1.5V/18Ah Alkaline batteries (included)
Weight
530g
(Daytime version 560g)
SnowWhite® chilled mirror hygrometer
Versions
Several variants of Snow White are manufactured:
The .daytime. Snow White system has the chilled mirror mounted in an internal duct to protect the sensor from daylight. The
circulation through the duct system is good once established, the speed of response of the Snow White is similar or better
than the operational radiosondes, but this good ventilation cannot be guaranteed until the test rig has accelerated up to
normal ascent rate for several minutes. At low temperatures, with relatively wet conditions in the lower atmosphere,
contamination can build up in the duct.
The .nighttime. Snow White eliminates the internal duct and the chilled mirror sensor is exposed directly in the atmosphere.
In some measurements ascents are preceded by continuous rain. In these circumstances, .daytime. Snow Whites with the
sensor in an internal duct is flown (also on the night) and some measures are recommended to prevent ingress of rain to the
chilled mirror sensor. In this case the rain protection kit is installed to reduce effect of liquid water flooding the sensor.
The conversion from dewpoint to relative humidity requires an accurate air temperature measurement. If the sensor is used
with SRS-C34 radiosonde, the same calibration is used for dewpoint and temperature measurement, which eliminates and
differential errors and leads to the best possible conversion.
A complete package including meteolabor SRS-C34 radiosonde and a complete low cost ground station, ARGUS37, is
available from meteolabor and presents the best in ease of use, handling and accuracy. Alternatively Snow White can
interface to different manufacturers radiosondes.
Warning
Do not use radiosonde in proximity to airport,
check your local regulations.
Ordering Information
Description
Night version
Daytime version
PTU-Radiosonde meteolabor SRS-C34 with Snow White
MRS-SRS-C34/002
MRS-SRS-C34/001
PTU-GPS Radiosonde meteolabor SRS-C34 with Snow White
MRS-SRS-C34/003
MRS-SRS-C34/022
PTU-GPS Reference-Radiosonde meteolabor SRS-C34 with
Snow White
MRS-SRS-C34/026
MRS-SRS-C34/040
Snow White sensor for VIZ MarkII Radiosonde
MRS-ASW35/01
MRS-ASW35/00
Snow White sensor for Vaisala RS80 Radiosonde
MRS-ASW35/12
MRS-ASW35/17
Snow White sensor for Modem Radiosonde
MRS-ASW35/09
MRS-ASW35/08
Snow White sensor for other Radiosondes
On request
On request
Rain protection kit
n.a.
MRS-ASW-Rain-Kit
Recommended Balloon, type and size for 30km height
MBA-TA1000
MBA-TA1000
Recommended Balloon, type and size for 20km height
MBA-TA500
MBA-TA500
Dimensions, SnowWhite
280 x 150 x 125
210 x 260 x 90 mm
Weight including Batteries, SnowWhite
Approx. 530g
Approx. 560g
Dimensions, Radiosonde
345 x 210 x 100 mm
345 x 210 x 100 mm
Weight including Batteries, SnowWhite+Radiosonde
Approx. 1150 g
Approx. 1180 g
Contact
Meteolabor AG
Hofstrasse 92
CH-8620 Wetzikon
Switzerland
Phone:
Fax:
E-Mail:
Internet:
+41 44 934 40 40
+41 44 934 40 99
info@meteolabor.com
www.meteolabor.com
© by Meteolabor AG
All rights reserved.
Content may change without further notice • 2008-09
SnowWhite_e