Cloudiness

Nimbus Clouds

Nimbus clouds appear thick and very dark in the sky. Also known as rain clouds, they indicate a heavy downpour of rain, hail, or snow. They also signal the onset of tornadoes.

Scientists use an instrument called nephelometer to measure the extent of cloudiness in the skies.

Humidity

Humidity refers to the amount of water vapor in the atmosphere. The more water vapor there is in the atmosphere, the higher is the humidity. If you were in a place with high humidity and you sweat a lot, you would find it very hard to cool off because the atmosphere is filled with water vapor and there is no room left in it to absorb your sweat as it evaporates.

Islands near the equator experience high humidity. The Philippines and Singapore are humid almost the whole year round.

Humidity is measured using an instrument called psychrometer, which is made up of two thermometers of the same size. One of these thermometers is soaked in a wet cloth while the other is left dry. The difference in the readings of the thermometers is the amount of humidity in the air.