SGER: Investigations of Cloud Condensation Nuclei

这是一笔小额的探索研究补助金(SGER)，用于支持云凝聚核的物理和化学性质的研究。这些实验将于2001-02年冬季在美国西南部的两个或三个山顶天文台进行。实验的中心是一种名为云凝聚核去除器(CCNR)的新型仪器。这是一个温度梯度扩散室，空气样本通过它缓慢地被抽取。它在两个温度不同的饱和平板之间流动，就像一条薄薄的层状带状物质。通过调节平板的温度来调节腔体中心的过饱和度。根据过饱和度的不同，当空气通过时，样品中的一些气溶胶被激活、生长并以液滴的形式在小室底部沉淀下来。将幸存的粒子的尺寸分布与进入小室的粒子的尺寸分布进行比较，以确定作为云凝结中心的粒子的尺寸。通过比较电子显微镜图像和暴露在过饱和前后的颗粒的化学成分，可能有可能更多地了解在云形成中活跃的气溶胶颗粒。该项目旨在解决目前观测到的气溶胶颗粒的物理和化学性质与它们的造云能力之间存在的差异。

This is a Small Grant for Exploratory Research (SGER) to support research on the physical and chemical properties of cloud condensation nuclei. The experiments will be conducted in the winter of 2001-02 at two, or possibly three, mountaintop observatories in the southwestern United States. Central to the experiment is a novel instrument called the Cloud Condensation Nuclei Remover (CCNR). It is a thermal gradient diffusion chamber through which an air sample is slowly drawn. It flows as a thin, laminar ribbon between two saturated plates having different temperatures. The supersaturation at the center of the chamber is regulated by adjusting the temperatures of the plates. Depending on the supersaturation, some of the aerosols in the sample are activated, grow, and settle out as droplets on the bottom of the chamber as the air moves through. The size distribution of the surviving particles is compared with that of the particles entering the chamber to determine the sizes of the particles that served as centers for cloud condensation. By comparing electron microscope images and the chemical composition of the particles before and after exposure to the supersaturation it may be possible to learn more about the aerosol particles that are active in cloud formation. The project is designed to resolve the discrepancies that currently exist between observations of the physical and chemical properties of aerosol particles and their cloud-forming ability.