The Emst Strngmann Forum

The Ernst Strungmann Forum is founded on the tenets of scientific independence and the inquisitive nature of the human mind. Through its innovative communication process, the Ernst Strungmann Forum facilitates the continual expansion of knowledge by providing a creative environment within which experts can scrutinize high-priority issues from multiple vantage points. The themes that are selected transcend classic disciplinary boundaries they address topics that are problem-oriented and of...

Introduction

In this chapter, we examine the physicochemical properties of atmospheric particles that determine which subsets of the ambient aerosol can serve as cloud particle precursors for both warm (liquid) and cold (mixed-phase and ice) clouds. We recognize that not only do the particle properties play a role in determining which particles participate in cloud formation, so do environmental variables such as the air mass thermodynamic history and vertical motions. For a discussion of this larger...

Major Ground Networks

AERONET (AErosol RObotic NETwork http aeronet.gsfc.nasa.gov ) is a federation of ground-based remote-sensing aerosol networks that was established in the mid-1990s by NASA and CNRS it was expanded thereafter through the efforts of national agencies, universities, and individuals (Holben et al. 1998). Using standards for instruments, calibration techniques, processing, and data distribution, individual sites are connected into a network. The basic instrument is a CIMEL sun sky photometer. Data...

CCN Activity of Aerosol Particles

The ability of an aerosol particle to act as a CCN (CCN activity) that is, its ability to induce water-vapor condensation and cloud droplet formation under a given set of conditions depends primarily on (a) water-vapor supersaturation, (b) dry particle size, and (c) hygroscopicity (soluble particles) or wettability (insoluble particles) (Seinfeld and Pandis 1998 Pruppacher and Klett 2000 McFiggans et al. 2006 Andreae and Rosenfeld 2008). In science and engineering, hygroscopicity is generally...

Laboratory Cloud Simulation

Frank Stratmann1, Ottmar M hler2, Raymond Shaw1'3, and Heike Wex1 1Leibniz Institute for Tropospheric Research, Leipzig, Germany 2Institute for Meteorology and Climate Research, Forschungszentrum Karlsruhe, Karlsruhe, Germany 3Michigan Technological University, Houghton, MI, U.S.A. Since the atmosphere offers only observation possibilities and does not permit the setting of initial and boundary conditions, laboratory studies are important tools to examine cloud processes under well-defined,...

Diffusion Turbulence

Air-sea gas exchange Entrainment Shallow cumulus Teleconnections Stratocumulus Convective systems weeks Figure 12.1 Depiction of the continuum of relevant cloud-related processes across the full range of spatiotemporal scales, showing the underlying categorical behavior (gray text) from which processes emerge. scales (i.e., the microscale), or through global warming attributable to additional greenhouse gases. These perturbed clouds include possibly all tropospheric clouds, including contrails...

Introduction Clouds and Earths Radiation Budget

Clouds greatly impact the Earth's radiation budget (ERB) because they reflect solar or shortwave (SW) radiation back to space and restrict the emission of thermal or longwave (LW) radiation to space. One conventional measure of this radiative effect is cloud radiative forcing (CRF) that is, the difference between actual radiation flux and what it would be if clouds were absent (Ramanathan et al. 1989). A more proper term might be cloud radiative effect, since forcing is usually reserved for...

Current Understanding and Quantification of the Effects of Clouds in the Changing Climate System and Strategies to

Anthropogenic aerosols are thought to exert a significant indirect radiative forcing because they act as CCN in warm cloud formation and as ice nuclei in cold cloud-forming processes. Haywood et al. (Chapter 19) address this issue by comparing the radiative forcing from the indirect effect of aerosols with those from other radiative forcing components, such as that from changes in well-mixed greenhouse gases. They highlight problems in assessing the effect of anthropogenic aerosols upon clouds...

AOD 550nm

Figure 3.3 Mid-visible aerosol optical depth (AOD) at 550 nm wavelength. Comparison between annual maps from global modeling (M), the merged product (X), and sun photometer gridded samples (A). Deviations to model simulations suggest AOD underestimates in global modeling. Figure 3.3 Mid-visible aerosol optical depth (AOD) at 550 nm wavelength. Comparison between annual maps from global modeling (M), the merged product (X), and sun photometer gridded samples (A). Deviations to model simulations...

Importance of Small Cloud and ERB Changes and the Difficulties in Measuring Them

Global climate is very sensitive to even slight changes in clouds and radiation, hence requiring very precise measurements of variations in these parameters. For example, an instantaneous doubling of CO2 (100 increase) would produce about a 4 W m-2 reduction in outgoing radiation flux, which is less than 2 of the 235 W m-2 in global mean outgoing radiation. Since the trend in CO2 concentration over the span of a few decades is much smaller than a doubling, the trend in ERB is also...