Classification of Clouds

Introduction

The aggregates of water droplets or ice or both formed as a result of the condensation of water vapor in the atmosphere at different heights is called a cloud.

There is continuous evaporation from the earth’s surface. Thus, the water, which is completely transparent and invisible, merges in the air. Then, this moist air cools and becomes fully saturated as it rises. After the dew point is reached, condensation occurs, due to which the water vapor present in the air turns into water droplets or ice. This is what we see from the earth’s surface in the form of clouds.

The size of water droplets is initially so small that they float in the air. But when the size of those drops increases due to various processes, then the airwaves cannot hold them, and they fall to the ground. This is called precipitation. There are many forms of precipitation such as drizzle, rainfall, snowfall, or sleet, etc. In this way, starting from the process of evaporation to precipitation, the water cycle is completed.

Classification of Clouds

There is a wide range of variations in clouds in terms of height, shape, color, and transmission or reflection of light. Baptist Lamarck is a pioneer in the field of classification of clouds, but Luke Howard, an English pharmacist, and the naturalist is given full credit to present a sound scheme of classification of clouds into main and secondary types in the year 1803. His classification was so well designed that it is still in use.

Consequently, the International Meteorological Committee offered a system for naming and identifying different types of clouds in the year 1895. The first International Cloud Atlas was published in the following year i.e., in 1896. The World Meteorological Organization (WMO) now publishes International Cloud Atlas. The characteristic features of the classification of clouds as presented by WMO and Howard are given below.

World Meteorological Organization has classified clouds based on

• their genesis and characteristic features, and
• altitude of their occurrences.

Based on altitude; clouds have been classified into high, medium, and low clouds as follow:

Cirrus Clouds

These clouds found at the highest altitude in the atmosphere are composed of tiny ice crystals. These clouds are visible from the ground during the daytime and look very soft and white like silk. The appearance of these clouds in the sky is a sign of dry weather. Cirrus clouds are found at the altitude of 3- 8 km over the poles, 5 -13 km in temperate regions, and 5-18 km in tropical regions.

Cirrocumulus clouds

These are high-altitude clouds with white color and have patches of small white flakes which are arranged in distinct groups or wavelike forms. They usually appear as ripples like sand ripples in desert areas.

Cirrostratus clouds

These high-altitude clouds are white and spread in the sky like milky thin sheets. Cirrostratus clouds are a thin white veil of cirrus cloud. They are composed of tiny ice crystals which refract the lights and hence a halo is formed around the Sun during the day and the Moon during the night when these clouds appear in the sky which is an indication of upcoming storms.

Altocumulus clouds

These clouds are brown or white or white and brown. They are characterized by wavy layers of globular form and are found in the form of lines, groups, or waves. They are individual masses of clouds that are fitted closely together in geometrical patterns. High globular groups of altocumulus is sometimes called sheep clouds or wool pack clouds. Such clouds formed on mountain peaks are called “banner clouds”.

Altostratus clouds

These are thin sheets of gray or blue color having a fibrous appearance. When they develop as a thick sheet, the sun and the moon are obscured, and they look like a bright spot behind the cloud. They do not form a halo around the sun and the moon. They cover the sky partially or fully or are smoothly distributed over the entire sky. Often there is a possibility of continuous precipitation either in the form of drizzle or snow because of these clouds.  

Nimbostratus clouds

Nimbostratus clouds develop very close to the ground surface and are dark in color. They are so compact and thick that there is complete darkness and copious precipitation. Nimbo is formed from the Latin word ‘nimbus’ meaning thereby rainstorm. They are associated with rain, snow, and sleet but are not accompanied by lightning, thunder, or hailstorms.

Stratocumulus clouds

These are grey or whitish in color. They are composed of globular masses that are usually arranged in lines, or waves of groups. They are normally associated with fair weather conditions, but sporadic rain or snow is not ruled out.

Stratus Clouds

They are dense, low-lying, and fog-like clouds. Often, they are formed due to the diffusion of the lower layers of fog or their upliftment. They are composed of several uniform layers. When these clouds are associated with rain or snow, they are called Nimbostratus clouds as referred to below.

Cumulus clouds

They are very dense, widespread, and dome-shaped like cauliflower, and have flat bases with black color. They are white woolpack cloud masses and relate to fair weather but sometimes they become thunderclouds.

Cumulonimbus clouds

These clouds are thunderstorm clouds. They show great vertical development and produce heavy rains, snow, or hailstorm with lightning, thunder, and gusty winds. They appear like mountains or huge towers and assume the shape of an anvil or vast plume. Sometimes precipitation occurring from cumulus clouds in summer is evaporated before reaching the ground surface. Such rain is called Virga.

You May Also Like

• Structure of the Atmosphere
• Sedimentary Rocks
• Types of Plateaus
• प्रजातियों के वर्गीकरण के आधार (Basis of Racial Classification)
• प्रजातियों का वर्गीकरण (Classification of Races)