As cloud condensation nuclei (CCN) in the atmospheric environment, dust particles not only play an important role in promoting the formation of clouds or precipitation but also are an important part of air pollution. The classical nucleation theory (CNT) explains the contribution of dust to vapor-liquid condensation, that is, it significantly reduces the relative humidity required for water vapor condensation [1]. Common condensation nuclei can be divided into insoluble and soluble according to the properties of components, including naturally formed dust (such as calcium carbonate, CaCO3) and artificially discharged inorganic salts (such as sulfate and ammonium salts) [[2], [3], [4]]. The study of the action process of these condensation nuclei in the atmospheric environment is of great significance for the understanding of the water cycle and environmental problems.

New aerosol particles with a size of 3–10 nm in the atmosphere have the potential to grow into condensation nuclei and eventually affect the formation of clouds [5]. The process of water vapor condensation has attracted the attention of a large number of researchers. Rykaczewski et al. imaged the condensation dynamics on the surface of a single complex particle by electron scanning microscope [6]. Song et al. studied water vapor condensation at the hydrophobic-hydrophilic interface (graphene/mica) and hydrophilic-hydrophilic interface (MoS2/mica) by in-situ thermally controlled atomic force microscopy [7]. These studies have made great contributions to the experimental observation of the interaction between water and concretion surfaces. However, the experimental observation at the initial stage of condensation is still very difficult, leaving place for studies using molecular dynamics simulations. Ou et al. studied the kinetic process of water condensation on a mica surface and found that the results were similar to the condensation process described by the Stranski-Krastanov growth model [8]. Jan et al. simulated the water quality regulation and evaporation process and compared the results with the condensation equation derived from the dynamic gas theory to clarify the compatibility [9]. Li et al. found that nanostructures are conducive to condensation, which is affected not only by the increase of surface area but also by the distance between the nanostructure surface and the cold end [10]. Moreover, a large number of studies on vapor-liquid phase transition (including condensation and boiling processes) have been completed by molecular dynamics simulation [[11], [12], [13], [14], [15], [16]], which show the practicability of this method.

With the increase of man-made electromagnetic waves content in the atmosphere, whether electromagnetic wave affects water vapor condensation is a noteworthy and interesting problem. Aragones et al. studied the anisotropy of dielectric response and the effect of external electric field on the water phase diagram for the first time [17]. Butt et al. found that the external electric field reduced the saturated vapor pressure, and proposed the extended Kelvin equation based on this [18]. The existence of an electric field will increase the system energy through dielectric response [17,18], affect the condensation rate by competing with the interaction between surface molecules [19], lead to hydrogen bond rearrangement [20], and change the diffusion behavior of nanodroplets on the solid surface [21]. These studies show that the external electric field is an important factor for affecting the water condensation phase transition, which is of great significance to explore the micro field effect. Unfortunately, most of these studies describe the field effect of the electrostatic field and do not consider the problem of electromagnetic waves. Electromagnetic waves, especially microwaves, also affect intermolecular interactions such as hydrogen bonds [22,23], and there may be thermal and non-thermal effects [24], which also indicate that electromagnetic fields may also have some effects on water vapor condensation.

In this study, we considered the influence of electromagnetic waves in the atmospheric environment on water vapor condensation, mainly the influence of time-varying electric field on intermolecular interaction. The condensation process of water vapor with different condensation nuclei under a time-varying electric field is studied by molecular dynamics simulation. The density change [25] of the system reflects the time of phase transition and is directly affected by droplet pressure. The change of hydrogen-bond number is consistent with the CNT, and the time-varying electric field has an obvious effect on it. The results show that the time-varying electric field affects the condensation rate by affecting the energy change and diffusion behavior in different condensed nuclear-water systems.