HALO left Sal Airport in the cape Verde Islands at about 1500Z and first did two short sampling legs in the Sahara dust layer at 6000 and 11000 feet. Climbing up to flight altitude after these legs showed that the highest dust concentrations today were at levels above 11000', a bit higher than the day before. Then came the long crossing over the tropical Atlantic, which took HALO through the inter-tropical convergence zone (ITCZ) with some big convective systems, which show up as white blobs over the Atlantic on the satellite image below. Elevated aerosol concentrations were observed above some of these large convective clouds and cirrus outflow anvils. An example is on the picture to the right.
On some of them, I could observe the typical wispy plumes of ice particles detraining from the cloud.
Coming closer to Manaus, there were beautiful cloud scenes, with cumulus clouds of all sizes, from little fair-weather clouds to big cumulonimbi with the characteristic anvil shape that results from ice particles being blown away downwind from the top of the storm cloud. In fact, this reminded me a lot of the first time I had come to the Amazon, about 30 years ago, on a flight south from Venezuela to Manaus, and seen these anvil clouds rising over the Amazon forest.