It is another time in our lifetime to celebrate the World Meteorological Day as a commemoration of the Convention creating the World Meteorological Organization. On this day, 23rdMarch, sixty-seven (67) years ago, the World Meteorological Organization (WMO)replaced the International Meteorological Organization (IMO), which was established in 1873.

2. Ever since, this day has been celebrated annually with a carefully selected theme matching the contemporary issues of our time. This year, the theme of the celebration is “UNDERSTANDING CLOUDS”. This theme is chosen to highlight the enormous importance of clouds for weather, climate and water.One may ask, what is cloud? A Cloud can simply be described as a visible mass of condensed water vapour floating in the atmosphere, typically high above the general level of the ground. They are made of water drops or ice crystals floating in the sky.  Simple as it may seem the processes leading to cloud formation are not that simple.

3. Clouds are central in weather observation and forecasting. Most weather phenomenon are linked to the presence or absence of clouds. Through observation and research over the years, scientists  have come to understand that cloud processes provide vital information in weather prediction, particularly for precipitations. Cloud types gives an indication of the thermodynamical processes involved, hence the form of  expected weather condition.

4. Similarly, from the climate perspectives, clouds  are one of the key uncertainties in climate change studies. Limited understanding of clouds contributes substantially to persistent biases in modelled circulation  systems i.e. how do clouds couple to model circulations in the recent climate, how will clouds respond to global warming or other forces, and how will they feed back on it through their influence on the Earth’s radiation budget? Clouds play a vital role in the water cycle and shaping the global distribution of water resources.

5. Clouds are broadly categorized into  low, middle and high levels based on the height above ground of the cloud base. They are also categorized based on their shapes. This year, the WMO is launching the new International Cloud Atlas. The international cloud atlas is the single authoritative and most comprehensive reference for identifying clouds.Its reputation is legendary among cloud enthusiasts and scientists. The International cloud atlas dates back to the nineteenth (19th) century with several revisions in the twentieth (20th) century. However, the last hardcopy revision took place thirty (30) years ago i.e. 1987. During these years, science has been advancing on many fronts, hence the latest revision of the Atlas. The 2017 edition has many updates including addition of fresh images contributed by meteorologists, cloud watchers and photographers all over the globe. In addition to the updates, the Atlas also contains newly classified cloud types and other meteorological phenomena such as rainbows, halos, ,hailstones etc. This 2017 edition of the International Cloud Atlas is being presented in a new form. For the first time in its history, the Atlas has been produced in a digital format and it is available online. Access to it can be via mobile devices and computers.