Meteorological concepts II. Cloud masses.

Cloud masses are not to be confused with water vapour, but are small "micro-droplets" of suspended liquid water floating in the air, ranging in diameter from 0.2 to 0.3 mm, or in solid form as ice crystals, depending on their height. In order for them to precipitate as rainwaterThey need to increase in size and be between 1 and 5 millimetres in diameter. As this moist air is less dense than warm air, it remains in the upper layers of the atmosphere and the warm air masses remain in the lower layers.

If clouds were made up of water vapour (water in gaseous form), they would not be visible because it is an invisible gas. In fact we perceive them as white because when sunlight hits the clouds, the small water droplets scatter the light and reflect all the colours, this mixture gives the colour white. If the clouds are very dense and thick, the light cannot pass through them completely, giving them a more greyish tone. The light travels undisturbed until it penetrates the atmosphere, then it collides with the particles that make up the atmosphere: dust, water droplets and crystals, salt and air-forming molecules (oxygen, nitrogen and noble gases). Nitrogen and oxygen scatter more of the blue and violet colour, which they emit in all directions, while they let the orange and red tones pass through in a straight line, giving a result of celestial skies.

In the evening, it would be the same if it were not for the fact that the sun is low. In this position, its rays travel through up to 10 times more atmosphere to reach our eyes than when it is at the zenith. Therefore, the blue tones are so scattered that they do not reach our eyes, while orange, red and yellow do. The more solid particles suspended in the air, the more colourful and saturated the sunsets are.

Having a weather station is the perfect tool to know both the environmental humidity and all the variables necessary for a proper management of the field.

• Davis self-aspirated weather station