雲物理是一門探索雲及降雨生成發展的基礎科學；從單一微小的雲粒子生成，到較大雨粒子的形成，以致於最後水粒子降到地表產生降雨。乃是一連串各種不同物理過程的結果，而大氣雲雨的發生不僅牽涉到大氣中水汽飽和度及雲凝結核特性外，也與雲內粒子之間的交互作用密切相關。雲物理學的主要範疇在於利用嚴謹的熱力學定律及物理理論來解釋雲內水相或冰相粒子生成及其成長的過程，並藉以說明它們與實際雲雨觀測的相關。這裡所討論的現象尺度常介於公分至微米之間（即雲內粒子可能的半徑大小），因此與探討雲內較大尺度空氣運動的雲動力學有所區別。

“Cloud Physics” is a fundamental science dealing with the formation and development of cloud and precipitation. Formation of cloud droplets, raindrops, and precipitation is indeed subject to different physical processes, and the development of cloud and rain relate not only to the atmospheric moisture and condensation nuclei but to the interactions among in-cloud droplets. The science of cloud physics is to utilize the related thermodynamic principles and physical theories to describe the processes of the formation and growth of in-cloud liquid and ice droplets and to explain the observed properties of clouds and rain. Note that, in contrast to “Cloud Dynamics”, which focus on a larger scale process of air motions within cloud systems, the horizontal scale of interested phenomena in “Cloud Physics” is usually confined within centimeters to micrometers, i.e., approximately the size of liquid and ice particles in clouds.