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Dust clouds are ubiquitous in the atmospheres of hot Jupiters and affecttheir observable properties. The alignment of dust grains in the clouds andresulting dust polarization is a promising method to study magnetic fields ofexoplanets. Moreover, the grain size distribution plays an important role inphysical and chemical processes in the atmospheres, which is rather uncertainin atmospheres. In this paper, we first study grain alignment of dust grains inthe atmospheres of hot Jupiters by RAdiative Torques (RATs). We find thatsilicate grains can be aligned by RATs with the magnetic fields (B-RAT) due tostrong magnetic fields of hot Jupiters, but carbonaceous grains of diamagneticmaterial tend to be aligned with the radiation direction (k-RAT). At a lowaltitude of $r<2R_{\rm p}$ with $R_{\rm p}$ being the planet radius, only largegrains can be aligned, but tiny grains of $a\sim 0.01\mu$m can be aligned at ahigh altitude of $r>3R_{\rm p}$. We then study rotational disruption of dustgrains by the RAdiative Torque Disruption (RATD) mechanism. We find that largegrains can be disrupted by RATD into smaller sizes. Grains of high tensilestrength are disrupted at an altitude of $r>3R_{\rm p}$, but weak grains can bedisrupted at a lower altitude. We suggest that the disruption of large grainsinto smaller ones can facilitate dust clouds to escape to high altitudes due tolower gravity and may explain the presence of high-altitude clouds in hotJupiter as well as super-puff atmospheres.

Grain alignment and rotational disruption by radiative torques in exoplanet atmospheres