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Knowledge Expectations for METR 3223
Physical Meteorology II: Cloud Physics, Atmospheric Electricity and Optics

Purpose: This document describes the principal concepts, technical skills, and fundamental
understanding that all students are expected to possess upon completing METR 3223, Physical
Meteorology II: Cloud Physics, Atmospheric Electricity and Optics. Individual instructors may
deviate somewhat from the specific topics and order listed here.

Pre-requisites: Grade of C or better in METR 3113, METR 3213, MATH 3113.

Students should have a basic understanding of the structure and thermodynamics of the atmosphere
and a basic understanding of electromagnetics prior to starting this course.

Goal of the Course: This course provides an overview of cloud and precipitation processes
including: the role of aerosols in cloud droplet and ice nucleation; development and application
of the Clausius-Clapeyron equation for phase changes; the transformation of cloud particles into
rain, snow, and hail by diffusion, collision and coalescence, and aggregation; cloud
electrification; lightning; optical phenomena, and elementary concepts of meteorological radar.

Topical Knowledge Expectations

I. Cloud Microphysical Observations
• Understand the relationship between physical processes in the atmosphere and the scales of
motion and features that can be identified. Know where micro-scale processes fall into this
distribution and how they feed back onto other scales.
• Understand the limitations of current state-of-the-art platforms and instruments used for cloud
• Be aware of the typical values of cloud particle characteristics in both convective and
stratiform clouds and why they are different.
• Be aware of the differences between maritime and continental cloud properties, the role of
aerosols in producing those differences, and its impact on cloud electrification.
• Understand the role of human activity on the sources and sinks of aerosols that are important to
cloud properties.
II. Cloud Droplet and Cloud Ice Nucleation
• Understand the derivation of the Clausis-Clapeyron equation and the limitations of its
• Know what is meant by supersaturation.
• Understand the difference in saturation over water versus an ice surface.
• Be aware of the effect of curvature on the equilibrium saturation vapor pressure over a cloud
droplet and how this affects the potential for homogeneous nucleation of a cloud droplet from pure
water vapor.
• Understand the effect of hygroscopic aerosols on the equilibrium saturation vapor
pressure over a cloud droplet.