A low-hanging layer of clouds obscures the sky today, and very little light illuminates the streets and gardens of our neighbourhood. I think about a passage in the recently published 'State of the Climate' report by the American Meteorological Society. It explains that, in 2023, there was more water vapour in the atmosphere than many years past, but also, "Despite this increased moisture aloft, 2023 had the lowest cloud area fraction since records began in 1980 with skies clearer globally. Consequently, the clouds reflected away to space a record small amount of shortwave radiation, but also blocked a record small amount of longwave radiation from leaving Earth. The overall effect was the weakest cooling effect of clouds on record". The report goes on to explain a global 'darkening' due to reduced sea ice and other ice-covered areas - here 'darkening' refers to the increased proportion of earth's surfaces that absorb light, rather than reflect it. At the same time, in the UK and across northern Europe, the changing and 'wobbling' route of the jet stream is bringing cloudier, stormier, wetter weather. As I peer up at the thick grey cloud, the term 'darkening' seems to register with many meteorological and more-than-meteorological affects. I manage to coax enough light from a table lamp into the microscope to see the veins of a fallen, yellow Plane tree leaf.