Heterogeneous nucleation rate (J) of methane ice near the 1.2 bar level in Uranus atmosphere, as a function of the CCN particle radius and the contact parameter. The horizontal dashed line indicates the range of sizes between 1 and 10 nm. The total number of CCN per cm⁻³ s⁻¹ is the product between the values illustrated in the figure and the concentration of haze particles for a given size.