All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 113 11 4
PDF Downloads 20 6 2

Distributions of Liquid, Vapor, and Ice in an Orographic Cloud from Field Observations

Taneil UttalWave Propagation Laboratory, Boulder, Colorado

Search for other papers by Taneil Uttal in
Current site
Google Scholar
PubMed
Close
,
Robert M. RauberDepartment of Atmospheric Sciences, University of Illinois at Urbana/Champaign, Urbana, Illinois

Search for other papers by Robert M. Rauber in
Current site
Google Scholar
PubMed
Close
, and
Lewis O. GrantDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado

Search for other papers by Lewis O. Grant in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

The phase distribution of the water mass of a cold orographic cloud into vapor, liquid, and ice is calculated from measurements made from an instrumented aircraft. The vapor values are calculated from thermodynamic measurements, and the liquid is measured directly with a Johnson-Williams hot-wire device. Ice mass is calculated from particle size spectra obtained with a two-dimensional optical array cloud probe (2-D probe) and a knowledge of crystal habit based on decelerator measurements and cloud temperatures. Maximum vapor mass in the cloud is 2.0 g m−3, which is comparable with maximum ice mass in the cloud of 1.5 G m−3. Maximum liquid mass is approximately one order of magnitude lower at 0.15 g m−3 and appears to be a small remainder between the vapor and the ice as they compete for the major portion of the cloud water mass. In the cloud upwind of the mountain, liquid + vapor + ice is nearly constant, suggesting that precipitation does not deplete the water mass at the levels studied by the aircraft. Maxima in both ice and liquid mass appear just over the windward crest of the mountain, indicating a strong orographic effect on condensation of vapor to liquid and growth of ice by vapor diffusion and riming. The distribution of crystal habits also suggests a significant downdraft exists just downwind of the mountain.

Abstract

The phase distribution of the water mass of a cold orographic cloud into vapor, liquid, and ice is calculated from measurements made from an instrumented aircraft. The vapor values are calculated from thermodynamic measurements, and the liquid is measured directly with a Johnson-Williams hot-wire device. Ice mass is calculated from particle size spectra obtained with a two-dimensional optical array cloud probe (2-D probe) and a knowledge of crystal habit based on decelerator measurements and cloud temperatures. Maximum vapor mass in the cloud is 2.0 g m−3, which is comparable with maximum ice mass in the cloud of 1.5 G m−3. Maximum liquid mass is approximately one order of magnitude lower at 0.15 g m−3 and appears to be a small remainder between the vapor and the ice as they compete for the major portion of the cloud water mass. In the cloud upwind of the mountain, liquid + vapor + ice is nearly constant, suggesting that precipitation does not deplete the water mass at the levels studied by the aircraft. Maxima in both ice and liquid mass appear just over the windward crest of the mountain, indicating a strong orographic effect on condensation of vapor to liquid and growth of ice by vapor diffusion and riming. The distribution of crystal habits also suggests a significant downdraft exists just downwind of the mountain.

Save