FORECASTING WEATHER USING CLOUDS
Using the clouds as a field-expedient indicator of forecasting weather, an individual can acquire a practical skill. Not only will this skill be helpful in a survival situation or in a self-reliant manner, but also in everyday life. Clouds can be utilized as likely indicators as to how weather may change. These indicators may be accurate several hours or days before the actual weather comes about. They’re a relatively simple concept to understand and help foster a sense of self-reliance in the fact that you can predict the weather locally without relying on others to interpret cloud formations.
HOW & WHY DO CLOUDS FORM
Clouds are composed of water; water having three forms: liquid, solid, & gas. The gaseous version of water is known as water vapor. Clouds occur when this water vapor changes back into liquid water (the process known as condensation). The water droplets forming as a result of condensation continue to increase in size until they are to large to remain airborne and become precipitation (rain, snow, hail, etc.). Searching the internet or book resources for more information about the science of clouds, or weather in general, will yield countless results if you’re interested to learn more.
TYPES OF CLOUD FORMATIONS
Clouds generally have two descriptive parts in there various names. The first part of the name typically refers to the height of the cloud while the latter portion describes the appearance. Keep in mind that the altitudes of clouds can have bases below 2km all the way to above 6km. There are a total of 10 cloud formations with basic descriptions, that are classified by the World Meteorological Organization. Below is a list of each formation with a brief description to help you recognize which cloud formation is appearing in the sky.
High Clouds (bases above 6 km)
- Cirrus – These high hanging clouds are wispy and formed by ice crystals which gives them a white appearance.
- Cirrocumulus – These clouds are often smaller, rounded masses, which look like rippled sand. Generally, they follow bad weather and eventually evaporate, leaving a bright, blue sky.
- Cirrostratus – Composed of ice particles and visually appearing like white veins in the sky. Larger Cirrostratus formations typically indicates better weather while smaller formations indicate increased probability of adverse weather.
Middle Clouds (bases between 2 and 6 km)
- Altocumulus – – Generally indicating fairer weather, these clouds are visually similar to Cirrocumulus clouds except they are larger, thicker, and typically not as white, with shadows.
- Altostratus – This greyish cloud is often described as being responsible for forming a “veil” which makes the sun/moon appear as a watery disc. If bad weather is approaching, this watery disc will disappear and the clouds will thicken & darken until precipitation occurs.
- Nimbostratus – Nimbostratus clouds appear as low, dark, blankets of cloud and can indicate that rain or snow is probable within 4-5 hours along with sustained rains.
Low Clouds (bases below 2km)
- Stratocumulus – Often this formation appears to cover the visible sky. Visually appearing as lumpy, low hanging, rolling masses, moving along with the entire sky. These e cloud types are oftentimes thin enough to allow the sun to filter through them. It’s possible for light precipitation to occur and they usually disappear in the afternoon and leave a clear, night sky.
- Stratus – Of all cloud types, these are the lowest. They appear as a uniform, fog-like layer in the air. These clouds are generally responsible for creating light “drizzle like” rain. When thickly formed overnight and cover the morning sky the next day, they are generally followed by fair weather.
- Cumulus – These are the easy to spot fluffy, white clouds. They’re associated fair weather when widely separated but if they become very large with multiple heads, they are an indication of high chances of sudden, heavy storms. Another indicator for this cloud type when at sea is if they appear in a cloudless sky, they’re a good indicator of land beneath them.
The final cloud type is unique because it can extend through all ranges of altitudes
- Cumulonimbus – If you can only remember 1 cloud type, remember this one as it’s often associated with more adverse weather such as hail, tornadoes, damaging winds, severe thunderstorms, etc. These clouds assume a dark and ominous appearance. These clouds may range all the way up to 6k km (20,000 ft) with the top forming a flat, “anvil top” shape.
Each cloud type can be used as an indicator for general weather behaviors. It’s important to note that generally, the higher the cloud formations, the more favorable the weather. Also, small, dark, clouds hanging closely beneath the stratus layer are a sign of possible showers or inclement weather. Finally, clouds near high ground are also generally associated with rain unless they clear out by the afternoon. Remember, weather is a system that follows basic patterns, but there’s always the chance of a “freak” storm. In a survival situation, or if communications such as television, radio, or the internet were to be disrupted, the self-reliant individual would have the ability to predict their local weather to help better plan for their day.
There are 10 cloud formations, and memorizing their basic appearance can help you predict the weather around you. Another way to help make it easier to know what type of cloud you’re seeing is by memorizing the Latin meaning which partially describes it.
Cirrus: from Latin, “fiber” or “hair”.
Cumulus: from Latin, “heap” or “pile”.
Stratus: from Latin adaption stratum, “layer” or “sheet”.
(Cumulo-, Cirro-, or Stratus-) Nimbus: from Latin, “cloud”.