Common experience is that if the temperature is lower than 0°C, then water will be in the form of ice instead of liquid. However, this is not true for the atmosphere, because many clouds with temperatures less than 0°C have super-cooled liquid in them. If these clouds also contain ice, they are called mixed-phase clouds. [...]

Marine boundary layer (MBL) clouds can regulate significantly the sensitivity of climate models, yet currently they are simulated poorly. This study aims to characterize the seasonal variations of physical properties of these clouds and their associated processes by using measurements from the Atmospheric Radiation Measurement (ARM) mobile facility (AMF) at Point Reyes, reanalysis products, [...]

Squall lines with trailing stratiform precipitation are common in both the mid-latitudes and tropics. These systems produce copious amounts of precipitation and occasionally severe weather. Because of their extensive size and frequent occurrence they are also important in redistributing energy in the atmosphere via convective and mesoscale transport and latent heating/cooling. However, their structure and [...]

Ice storms and tornadoes were not enough to stop a team from the Pacific Northwest National Laboratory who traveled to Oklahoma in January to begin an aircraft field study on thin clouds. The researchers are gathering direct measurements from thin, low-lying clouds as part of a field campaign from January to June 2009 that will [...]

A mathematical tweak dramatically improves air pollution detection on cloudy days. Scientists at Pacific Northwest National Laboratory have devised a way to reduce cloud-induced glare by as much as ten-fold in some cases when satellites measure atmospheric pollution on cloudy days. Satellites monitor the pollution level in the atmosphere by measuring the amount of [...]

An 80-person team of U.S. and Canadian scientists flew over the North Slope of Alaska in an intensive month-long field study in April. The group's mission was to measure and detail key elements of the atmosphere to help reveal how the Earth's climate is changing. The Arctic region is an ideal study location because it [...]

Arctic mixed-phase clouds are complex because they consist of both ice and water. Although these clouds play an important role in Arctic climate change and the energy balance, they have not been understood well and are not well represented in current climate models. Understanding how mixed-phase clouds form and what affects their lifetime [...]

The increase in anthropogenic CO2 explains about half of the observed warming over the past 150 years and cannot satisfactorily explain the geographic variation in the warming. Of all the key uncertainties on climate forcing, the indirect effect of aerosols on clouds and radiation ranks at the top (IPCC 2007). Ice nuclei (IN), a class [...]

Clouds come in a variety of shapes and sizes, and each type contributes differently to the climate system. While low-level water clouds tend to have a cooling effect on the atmosphere, high-level cirrus clouds that are composed of ice can have the opposite effect. Located in the upper layer of Earth's atmosphere--the troposphere--these icy clouds [...]