You don’t need sophisticated instruments to make fairly sound weather predictions – especially if you know a few basic principles – and can read the local skies (and other natural clues such as animal behavior and other physical signs). At least you should know when Mother Nature is waving her meteorological yellow flag!
Let’s start with cloud cover. Generally, high clouds tell of upcoming weather – ice crystals are from moisture in the air generated by distant storms often meaning fair weather further down range. Low clouds are a manifestation of current weather in the immediate area. The middle range clouds are indicative of the “weather” over a greater area or region.
There are three basic categories of cloud formations:
High clouds Cirrus/“horsetails”, Cirrostratus: thin veil of ice crystals/“sun dog” halos, Cirrocumulus: tiny cotton balls/rippled sand;
Middle clouds: Altostratus: light gray veil/blocks the sun. Altocumulus: lumpy/“flock of sheep”;
Low clouds: Cumulus: puffy clouds, Stratus: straight, layered clouds, Stratocumulus: puffy clouds, clustered/partially separated or layered; Nimbostratus: dark clouds not usually visible from directly below.
Air, Pressure, etc. – Changes in the air’s temperature affects how it moves. Warm air rises forming a partial vacuum that creates a low pressure at the surface of the earth. That rising air begins to expand and get cold (often forms clouds). As air starts to sink again, it warms up and starts to pile up at the earth’s surface thereby creating high pressure. Winds blow from high pressure to low pressure.
Lines of equal pressure around either a high or low area look like a contour map. Those lines are much closer together around a low pressure area. Since the air flows from high to low it flows from the wider contours to narrower ones, creating higher winds because of the steeper, downward slopes of those narrower contour lines.
Besides temperatures causing air to rise, obstructions on the surface do, too (i.e. mountains, bluffs, escarpments).
Generally then, higher pressure means drier, warmer conditions; lows mean rain, winds, etc. Highs circulate winds clockwise; lows circulate counter-clockwise.
Mother Nature’s Weather Forecaster:
Low pressure causes insects and birds to fly lower than with high pressure; bees tend to be more active before fair weather. A vertical column of smoke is a sign of fair weather whereas smoke that tends to flatten out indicates poor weather. Odors are more noticeable and sound seems louder and sharper in low pressure air.
Halos around the moon and sun (called Moon or Sun Dogs) are also good indicators of impeding weather: rain before the night is done – sun dog; or rain by the following noon- moon dog. Also, sharp, clear images of the moon, and bright, twinkling stars means there is little moisture in the air.
Knowing all the ways winds can be generated is important – temperature, obstructions and other weather elements all affect the movement of air (wind).
Anywhere there are high, sheer bluffs, cliffs or steep mountains adjoining the water’s edge can generate williwaws – winds that literally spill down off of the high country like water overflowing a sink. These sudden gusts can come out of nowhere and cause an unsuspecting and unready kayaker to capsize.
During the day, as the sun heats air over land, the sea/lake is cooler. This causes the cooler, sea/lake air to flow in to replace the rising, warm air over land. At night, the land cools faster than the waters and the wind shifts to flow back out to the sea/lake.
Learning weather signatures and what to expect will help you make safer decisions when it comes to planning any outdoor activities, course selection and alternate option needs. A good weather radio is an essential piece of equipment for even outdoor adventures. Small barometers are also a good bet, especially those that will track readings in eight-hour segments to show changes in rate and amount of change in pressure.
Basic knowledge of weather patterns is an essential part of being self-reliant in the outdoors.
Be Smart; Be Safe; Have Fun!