University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
The University of Wisconsin Collection

Page View

Smith, Robert (ed.) / The Wisconsin engineer
Vol. 70, No. 6 (March 1966)

Science highlights,   pp. 34-37


Page 35


of the National Aeronautics and
Space Administration sponsored
the research.
  The fingerprints-clear patterns
of the light-reflecting and absorb-
ing properties of the two types of
frost at wavelengths in the in-
frared spectra to be obtained from
Venus in future space probes. They
may also aid in climatic studies
of the planet. For example, it is
not now known why the clouds
surrounding Venus apparently re-
main at the same temperature,
both on the bright side of the cloud
cover reflecting the sun's rays, and
on the dark side away from these
rays.
  To achieve accurate measure-
ments, the investigators used a
special reflectance attachment on
a high-resolution  spectrophoto-
meter. The attachment excluded
the radiant energy emitted by the
specimens. The inclusion of such
emission, which only affects
NOISE DATA -CARD SITE (NBS)
WIND DATA -WASH. D. C. NAT'L. AIRPORT
        FEB. 11, 1959
NOnSF I FVFI SAMPI F RFAfl IIT 'ZA
717"TP'777fr' 9I f7 Ppr'F -7 l
.190  1800  .....           I0QQ... O.
  Fig. 1-Infrasonic noise data obtained locally by NBS over a period of nine
hours
are compared with U. S. Weather Bureau wind data derived for the same period.
The comparison shows that noise power levels, obtained by a technique devised
by
the NBS staff, and wind velocities rise simultaneously.
            WAVELENGTH (H1)
25    3      4     5
4000
3000    2000
  WAVENUMBER (cm')
  Fig. 2-Infrared spectral rel
of carbon dioxide frost obtained
also at a temperature of -196
spectrophotometric measur
in the infrared, would han
torted experimental results.
  Four types of specimens N
vestigated: (1) frost collecte
             WAVENUMBER (-')
 Fig. 3-Infrared spectral re]
 of crushed "dry ice" obtained a
perature of -78'C (the sub
temperature of carbon dioxide).
10 20    nfmrn nh Pri0 wer 1-iinnr nn C
          super-cooled base; (2) water at
          room temperature-for comparison
          purposes; (3) carbon dioxide frost
          formed on a super-cooled base in a
          closed  container of evaporating
          solid  carbon  dioxide; and  (4)
          crushed commercial "dry ice," i.e.,
          solid carbon dioxide.
10o0        The method of specimen prep-
          aration did not rule out contamina-
iectance  tion of the water frost with the
at NBS,   carbon  dioxide frost, and  vice
IC.
          versa; however, no common fea-
ements   tures were found in the resulting
ye dis-   spectra of the various types of
          specimens. It therefore appears
,*re in-  that the samples were essentially
'ere in-  uncontaminated. Moreover, the
d from    spectra of both the carbon dioxide
          frost and of the crushed dry ice
were strikingly similar at all signif-
icant wavelengths.
  The study was carried out for
Prof. John D. Strong of the Johns
Hopkins University's astrophysics
laboratory. Prof. Strong recently re-
ported on measurements of the
spectral reflectance of Venus ob-
tained across part of the infrared
from balloon-telescope flights in
109A     Up Ho -nel-r Ahrtr  n
           LCu-t. lit: a     'JaJll'LA. alPt.a.Jl'y ".A1-
           rections for absorption by residual
Flectance water and carbon dioxide vapor in
timation  the upper atmosphere of Venus to
           these measurements. From the re-
MARCH, 1966
sults, he concludes that the planet's
clouds are composed of ice crystals.
  Water frost data obtained in the
present study confirm Prof.
Strong's laboratory findings, al-
though not in complete detail. The
NBS measurements, however, on
both water frost and solid carbon
dioxide were made over a much
larger infrared region than were
Prof. Strong's measurements. They
therefore supply a basis for more
extended checks of the composi-
tion of the Venus cloud cover in
future probes.
    WINDS ARE NOISY . . .
    in the Inaudible Range
  A direct relation between high-
velocity winds and infrasonic noise
in the atmosphere has been found
at the National Bureau of Stand-
ards Institute for Basic Standards.
In this work, the NBS acoustics
laboratory compared local wind
velocities measured by the U.S.
Weather Bureau with infrasonic
noise measurements made at NBS
over the same time intervals. The
comparisons showed that large
changes in wind direction or peak
wind gusts accompanied high in-
frasonic noise levels, thus indicat-
ing noisy winds even in the in-
audible range.
                                35
t30 _
           CARBON DIOXIDE FROST
:,60 -
40
120
      I
_A tA11 V J IJ 11WA tv we CAtt V >,1 WA1 a
.
II
I
I
1
U
I


Go up to Top of Page