Category: 1. Introduction to convective weather

1.1.2.3. Measures of convective instability

Measures of convective instability There are many different kinds of measures of convective instability. The most common, and you will come across in virtually an in-depth forecast or storm chaser discussions, is CAPE = Convective Available Potential Energy. Chances are you have heard storm chasers and enthusiasts talk about this...

1.1.3. Different types of convective clouds – from fair weather clouds to thunderstorms

Convection forms distinct types of clouds. Convective clouds are divided into two types (genera): cumulus and cumulonimbus. Each successive type and species displays more vertical development as a result of more convective energy being available. The more convective energy is available, the higher the convective cloud will reach. In terms...

1.1.3.1. Cumulus humilis – fair weather clouds

CUMULUS HUMILIS Cumulus humilis, also known as fair weather clouds are the smallest convective clouds and the first stage in development of convective clouds. They typically form at 500 to 3000 m altitude and have limited vertical development. Cumulus humilis rarely produce any type of precipitation. You can spot these...

1.1.3.2. Cumulus mediocris

CUMULUS MEDIOCRIS Cumulus mediocris develop from Cumulus humilis and display more vertical development, up to 3000 m altitude. They generally do not produce precipitation, although virga or light rain can occur. They can develop into larger Cumulus congestus clouds.                     

1.1.3.3. Cumulus congestus (Towering cumulus)

CUMULUS CONGESTUS Cumulus congestus clouds form in deep moist convection, as an intermediate stage between cumulus mediocris and cumulonimbus – a cumulus mediocris will grow into a cumulus congestus if enough convective energy is available. In aviation cumulus congestus is also known as towering cumulus (International Civil Aviation Organization). Cumulus...

1.1.3.4. Cumulonimbus (calvus, capillatus, incus) – thunderstorms

CUMULONIMBUS CALVUS Cumulonimbus calvus is a form of Cumulonimbus cloud with a sharp, rounded, billowing top, still rising. It develops from Cumulus congestus. Cumulonimbus clouds, by definition, contain ice crystals – they are present in cumulonimbus calvus, but still in relatively small quantities. Cumulonimbus calvus develops further into Cumulonimbus capillatus...

1.1.3.5. Examples of convective clouds – how to distinguish them visually

EXAMPLES Convective clouds can present a considerable range of appearances, depending on their type, size and strength of updraft. The following examples encompass much of the variety of convective clouds. Each example includes a photo of a convective cloud or multiple convective clouds with argumentation for their name. Vertical development:...

1.2. Thunderstorms

In this section we are going to take a general look at thunderstorms. What is a typical thunderstorm. We will take a thunderstorm apart into its basic components and how they make the thunderstorm work.                     

1.2.2. Updraft and downdraft

A thunderstorm (or even a rain shower for that matter) is organized into two main components: updraft and downdraft. The updraft is the rising warm, moist air within the thunderstorm. The downdraft is the descending cooled air, containing precipitation. We first take a look at the updraft.