Meteorologists study the weather. To do this they use sophisticated instruments; but, experienced mariners can predict the weather just by observing the clouds. This boating safety tip will help you understand how to read the clouds and decipher the messages they send. HIGH CLOUDS … High level clouds occur above about 20,000 feet. Due to cold tropospheric temperatures at these levels, the clouds primarily are composed of ice crystals, and often appear thin, streaky, and white (although a low sun angle, e.g. near sunset can create an array of color on the clouds) The family of high clouds are … Cirrus Clouds … These are usually white and predict fair to pleasant weather. By watching the movement of cirrus clouds you can tell from which direction weather is approaching. When you see cirrus clouds it usually indicates that a change in the weather will occur within 24 hours … Cirrostratus Clouds … Cirrostratus clouds are thin, white clouds that cover the whole sky like a veil. These clouds are most commonly seen in the winter, and can cause the appearance of a halo around the sun or the moon. Weather prediction: Rain or snow will arrive. Within 24 hours … Cirrocumulus clouds… Cirrocumulus clouds are usually seen in the winter and indicate fair, but cold weather. In tropical regions, they may indicate an approaching hurricane. … MIDDLE CLOUDS … These are Clouds that signify clouds within bases between 6500,and 23,000 feet. At the highest altitudes, they may also have some ice crystals, but they are composed mainly of water droplets. The family of middle clouds include … Cumulonimbus Clouds … These forecast heavy rain, hail, snow, thunder storms, tornadoes, or even hurricanes … Altocumulus Clouds … Altocumulus clouds are associated with unstable weather conditions. If you see one of these during the morning, you should expect a thunderstorm in the morning. … Altostratus Clouds … Altostratus are large mid-level
Sheets of thin cloud. These are usually composed of a mixture of water droplets and ice crystals, they are thin enough in parts to allow you to see the Sun weakly through the cloud. They are often spread over a very large area and are typically featureless conditions. If you see one of these during the afternoon, you should expect thunderstorms in the afternoon … LOW CLOUDS … Low clouds occur below 6500 feet, and normally consist of liquid water droplets or even supercooled droplets, except during cold winter storms when ice crystals (and snow) comprise much of the clouds. The family of low clouds includes … Stratocumulus Clouds … Stratocumulus clouds are low level clumps or patches of cloud varying in color from bright white to dark grey. These are the most common clouds on earth. They are defined well defined bases, with some parts darker than others. They usually have gaps between patches of clouds, but they can be joined together as well. Stratus Clouds … These clouds always bring rain or snow. Sometimes the precipitation is a light mist or drizzle. The word Stratus means “layer” and these clouds often look like a blanket in the sky. The tops of these clouds are mostly brilliant with white ruffles when lit by the Sun, although their base is usually mostly dark … Nimbostratus Clouds … Nimbostratus clouds are dark grey, they have featureless layers of cloud formations so thick they block out the Sun. These clouds bring persistent rain, and are associated with frontal systems provided by mid-latitude cyclones. Nimbostratus clouds are the least picturesque of all main cloud types … Cumulonimbus Clouds … Commonly known as thunderclouds, these are the only type of cloud that produce hail, thunder and lightning … Cirrocumulus Clouds … Cirrocumulus clouds are most often seen I the winter and indicate fair, but cold weather. In tropical regions, they may indicate an approaching hurricane … FOG … In general, fog forms when the air is equal to or below the dew point temperature. It is a kind of cloud that touches the ground … Advection Fog … This is the fog that is most commonly encountered at sea. It is produced when warm, moist air passes over the warmer sea’s surface … Radiation Fog … This fog forms on land during clear and calm nights. As the land becomes cooler, it cools the air immediately above the land’s surface. This fog forms primarily at night and brings with it a light breeze … BAROMETERS … Instruments measuring atmospheric pressure. These are especially helpful when forecasting the weather … A… The direction and rate of change of barometric pressure indication on the barometer is very meaningful in forecasting weather …B… A barometer showing falling pressure indicates the approach of a low pressure system … C … As a high pressure system approaches, the Barometer reading rises … D … A slow gradual fall of the barometer indicates approaching deteriorating or unsettled weather … E … A rapid rise or fall of the barometer indicates approaching deteriorating or unsettled weather … F … A rapid rise or fall of the barometer indicates a change in the present weather conditions …G … The barometer is an instrument for measuring the atmospheric pressure … H … The purpose of the set hand on an aneroid barometer is to indicate change in the reading of the barometer … I … A rapid change in barometric pressure usually indicates strong winds.