This is the floating mass of minute water — droplets or ice — crystals that are produced by condensation of freezing of water vapour on particles of dust, smoke and salt. Places of equal degree of cloudiness are joined by lines known as ISONEPHS. There are about four types of cloud namely:
- High Clouds
- Medium Clouds
- Low Clouds
- Clouds with Vertical Extent.
Cloud is measured with cloud searchlight.