Round-up: Weather

The 23rd of March is World Meteorological Day, and in 2018 the World Meteorological Organization has declared the theme to be “weather-ready, climate-smart”. Here at Cosmos we’re fascinating by clouds, rain, wind, sunshine and the complex science that explains them all – not to mention the long-term climatic trends.

Below is a selection from the archives of stories about weather (and a bit of climate) to help you stay ready (and smart). 

Some basics

  • Where does wind come from? Like a lot of things that happen on Earth, wind is ultimately caused by the Sun – but the details are fascinating.  
  • Why do clouds float? Clouds are made of tiny droplets of water, and water is heavier than air – so why don’t they fall down as rain straight away? 

Recent discoveries

  • Rainforests can make their own rain. According to a 2017 study, wet season in the Amazon rainforest is triggered early by water vapour released by the forest’s trees themselves through transpiration.  
  • Last year, the World Meteorological Organization recognised new types of clouds for the first time in more than half a century. One of them was the spectacular Asperitas, a hypnotically waving form that looks like an upside-down ocean. Check out a video.  
  • The recent northern winter saw snow fall on the hills of the Sahara for the second time in three years. 


  • Hot days are becoming more common, and so are strings of hot days one after the other. Even one degree of global warming could translate to more than a month of extra heatwaves each year in some places. 
  • Spring is coming a little earlier each year, as shown by – among many other things – earlier and earlier blossoming of the cherry trees in Kyoto, Japan.


  • Earth isn’t the only planet to have fascinating weather. The Juno probe, currently in orbit around Jupiter, has been sending back stunning pictures of spectacular storms and cyclones that dwarf anything on our planet. 

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