Abstract The vertical structure of relative humidity within cirrus clouds in the upper troposphere remained unexplored, owing to measurement challenges. Twelve years of balloon‐borne simultaneous measurements of upper tropospheric humidity and optical particle backscatter during the Asian summer monsoon are used to consolidate our understanding of cirrus. Thin cirrus are typically supersaturated with respect to ice (median RHi ≳ 100%) in their upper parts, have a median RHi ≈ 100% toward their center, and RHi 140% enables homogeneous nucleation. Thicker cirrus show higher backscatter, indicating numerous particles that likely nucleated homogeneously in deep convection. These clouds slowly evaporate, as evidenced by slight subsaturation (RHi ≲ 100%) throughout their vertical extent. Cloud‐base RHi ≈ 70% suggest rapid crystal settling and evaporation. This data set may serve as reliable microphysical reference.
Observations from the Little Bunker
Last updated: December 27, 2025 02:09 PM
Atmospheric CO₂
427.7 ppm
+17.9
ppm/year
Atmospheric CH₄
1930.95 ppb
+-3.5
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year