Automatic cloud condensation nuclei counter

Abstract

Abstract AN APPARATUS AND METHOD FOR THE AUTOMATIC MEASUREMENT OF THE CONCENTRATION OF CONDENSATION NUCLEI CONTAINED IN AN AIR SAMPLE THAT FORM CLOUD DROPLETS UNDER CONDITIONS CLOSELY APPROXIMATING THOSE OF NATURAL CLOUDS. AN AIR SAMPLE CONTAINING CONDENSATION NUCLEI IS INTRODUCED INTO A THERMAL DIFFUSION CHAMBER WHICH IS MAINTAINED AT A SUPERSATURATION APPROXIMATING THAT OF NATURAL CLOUDS AND THE CONDENSATION NUCLEI ARE ALLOWED TO GROW TO A CERTAIN UNIFORM SIZE. THE DROPLET SIZE IS MEASURED DIRECTLY BY MEANS OF A PHOTOCELL OBSERVING THE LIGHT SCATTERED BY THE DROPLETS AT A FORWARD ANGLE FROM A MONOCHROMATIC LIGHT SOURCE. WHEN THE DROPLETS REACH THE DESIRED SIZE, AN ENCHANCEMENT IN SCATERED LIGHT OCCURS WHICH IS DETECTED BY THE PHOTOCELL. ALTERNATIVELY, THE DROPLET SIZE IS MEASURED INDIRECTLY BY A TIMER WHICH DEFINES A FIXED TIME INTERVAL AFTER THE AIR SAMPLE INTRODUCTION, GIVEN THE SUPERSATURATION IN THE THERMAL DIFFUSION CHAMBER. AN ELECTRICAL SIGNAL FROM EITHER THE PHOTOCELL OR THE TIMER THEN TRIGGERS AN INTEGRATING NEPHELOMETER WHICH SIMULTANEOUSLY MEASURES THE EXTINCTION COEFFICIENT DUE TO LIGHT SCATTERING OF THE CLOUD DROPLETS. THE KNOWN DROPLET SIZE AND OBSERVED EXTINCTION COEFFICIENT ARE COMBINED IN A SIMPLE MANNER TO DETERMINE THE CONCENTRATION OF CLOUD CONDENSATION NUCLEI.

Inventors

• 👤 Lawrence F Radke
• 👤 Peter V Hobbs

Bibliographic Details