# Water Vapour Imagery Pallet - Chapter I

## Print Version

## Chapter I: Introduction

### Table of Contents

- Chapter I: Introduction
- Introduction

### Introduction

This training module covers the interpretation of patterns in WV imagery from the SEVIRI sensor onboard Meteosat Second Generation (MSG) satellites. WV imagery is an excellent tool for diagnosing upper troposphere dynamics. While the lower and mid-troposphere are the origin of many everyday meteorological phenomena (such as rain, hail, thunderstorms, etc.), most of these phenomena are triggered by processes occurring in the upper levels of the troposphere. Therefore, the focus of this training module will be on dynamical processes like cyclogenesis, jets and upper level frontal zones. For the basic radiation principles concerning the two WV channels available on MSG, please refer to our training module on Water Vapour channels.

Figure 1: Invisible water vapor condenses to form visible clouds of liquid water droplets (source Wikipedia)

To better understand dynamical processes in the upper troposphere, the concept of Potential Vorticity (PV) is crucial. The numerical field of PV is reflected in the grayscale tones of WV imagery, which offers the first hint of the strong connection between the two. It is the aim of this training module to show the relationship between the concept of PV and the ongoing dynamical processes in the troposphere seen in the WV images.

* TECHNICAL NOTE: For the best interactive experience throughout this module please use the most recent versions of Firefox or Internet Explorer browser!