Knowledge of the temporal and spatial distribution of water vapor and liquid water in the troposphere is fundamental for shortand medium-range prediction of precipitation and severe weather. Current measurements of these quantities in the troposphere are limited by optical extinction in clouds (lidar), in temporal resolution (radiosondes), in spatial resolution (GPS networks) and in spatial cov...

Water is a nearly miraculous molecule that enters into the operation of the climate system in a remarkable variety of ways. A wide-ranging overview can be found in Pierrehumbert (2002). In the present chapter, we will be concerned only with the radia-tive effects of atmospheric water vapor on climate, and with the kinematics of how the water vapor distribution is maintained. These effects are i...

The 6.7)m channel water vapor (WV) images from GOES have been generally used as a tool for synoptic scale weather analysis since their availability in the early 1980's. However, WV images do have mesoscale applications as well. The availability of hourly WV images starting in late 1987 has permitted the monitoring of changes in mid and upper level moisture in the environment of convective storm...

Determination of the water vapor continuum absorption from 0.35 to 1 THz is reported. The THz pulses propagate though a 137 m long humidity-controlled chamber and are measured by THz time-domain spectroscopy (THz-TDS). The average relative humidity along the entire THz path is precisely obtained by measuring the difference between transit times of the sample and reference THz pulses to an accur...

We present an experimental study of the self- and N(2)-broadened H(2) O continuum in microwindows within the ν(2) fundamental centered at ~1600 cm(-1). The continuum is derived from transmission spectra recorded at room temperature with a BOMEM Fourier transform spectrometer at a resolution of ~0.040 cm(-1). Although we find general agreement with previous studies, our results suggest that ther...

An optical technique to characterize the accretion of material by microparticles is described. Experiments on the absorption of water vapor by single levitated polystyrene microparticles are reported as examples of an application of the technique. The optical resonant frequencies of the microparticles are perturbed by the accretion of material and the observed shifts are used to characterize th...

Very sparse data have previously limited observational studies of meteorological processes in the Sahara. We present an observed case of convectively driven water vapor transport crossing the Sahara over 2.5 days in June 2012, from the Sahel in the south to the Atlas in the north. A daily cycle is observed, with deep convection in the evening generating moist cold pools that fed the next day's ...

New Rayleigh-scattering optical thickness values for the terrestrial atmosphere in the 260 < lambda < 1500-nm wavelength range have been calculated using updated data on atmospheric optical parameters. The calculations include molecular scattering from water vapor and take into account varying atmospheric composition with altitude. The new Rayleigh-scattering coefficients average 4.5% lower tha...

Water dimers (H(2)O)(2) are believed to affect Earth's radiation balance and climate, homogeneous condensation, and atmospheric chemistry. Moreover, the pairwise interaction which binds the dimer appears to be of paramount importance for expounding a complete molecular description of the liquid and solid phases of water. However, there have been no secure, direct observations of water dimers at...