Clouds can be one of the best weather indicators around you. Even though there are no absolutes when it comes to weather prediction, recognizing some of the following cloud formations could give you some indication as to what is happening weather-wise.

First let's start off with, what is a cloud? Clouds are Air that is saturated in humidity and that condenses around dust particles and gathers to form a cloud. In other words, clouds are vapor.

There are 3 main heights of clouds:

Low heights, the ‘cumulus and stratus’ - Middle heights, the ‘alto’ - Top heights, the ‘cirro’.

Here are some of the clouds that are useful to be able to assess short or medium term weather changes. All cloud types can be found in the eCourse Weather and Tides on our website.

Fair Weather Cumulus: Puffy, small, low height clouds appearing during warm days. When they appear in a high-pressure, this is a sign of potential sea breeze or thermal activity on land. They can be frozen depending on the altitude. They can also appear during low-pressure and be the start of Cumulonimbus.

Cirrus: High-level clouds. Cirrus are an early sign of a low pressure system approaching. They look like hair and look like it is stretched by winds. Their thinness is of some centimeters and are formed from ice crystals.

Cirrostratus: Cirro means superior. Like Cirrus, they are high-level clouds appearing in layers. They make the sky appear whiter and at night it makes a halo visible around the moon. They usually indicate that a low-pressure system is coming.

Altostratus: Similar to Cirrostratus, they make a layer through which we can see the sun but no halo phenomenon. Rain or snow may occur later.

Nimbostratus: They are the largest cloud type. They can make rain for days! So thick that sunlight cannot pass through them.

Stratus: Are low-level horizontal layering clouds. These clouds are essentially above ground fog, formed either through the lifting of morning fog or through cold air moving at low altitudes over a region.

Alto cumulus: Also called pre-storm clouds, they look like several cumulus attached together. Thunderstorms may occur later.

Cumulus: Cauliflower-shaped low-level clouds with dark bases and bright tops. When observing cumulus, you are actually observing the condensation process of rising thermals or air bubbles at a certain level in the atmosphere known as the condensation level.

Cumulus Congestus: A form of Cumulus cloud that achieves considerable vertical development in areas of deep, moist convection. They are an intermediate stage between Cumulus and Cumulonimbus.

Cumulonimbus: These start as a Cumulus and become larger and larger. They develop until it makes an anvil shape as it reaches around 10 to 12 km in height. Cumulonimbus can generate storms, hail, heavy rain, tornados, and squalls. They can move against the wind and in any direction. You may not always see them due to the cloud cover. Remain aware of the ‘black sky’ (when it starts to be dark during a warm summer day).

If you find any of our tips helpful; all this and more is learned during an IKO Assistant Instructor Training Course. Check out the training calendar on the main IKO website to book your spot at a training course happening somewhere in the world!