Temperature is how hot or cold something is as measured on a definite scale. CBIBS buoys measure air temperature in degrees Celsius and convert this measurement into degrees Fahrenheit. Technically, heat is an indicator of the kinetic energy, or energy of motion, of the gasses that make up the air. As gas molecules move more quickly, air temperature increases. CBIBS buoys report air temperature as a six-minute average.
Barometric pressure—or air pressure—is the weight of the overlying air pressing down on the Earth. Barometric pressure is usually reported in inches mercury—inches Hg. Low barometric pressure means air is rising, while high pressure means the overlying air is sinking. Barometric pressure affects water chemistry and weather. Generally, high pressure (± 31 inches Hg) supports sunny, clear weather. Low pressure (~ 28 inches Hg) promotes rainy and cloudy weather conditions. Big changes in barometric pressure indicate big changes in weather. Barometric pressure can also affect the amount of a gas that can dissolve in water. When barometric pressure is high, more oxygen can be dissolved into the waters of the Bay; when the pressure is low, less oxygen can be dissolved into water. CBIBS buoys report barometric pressure as a six-minute average.
Chlorophyll is the main chemical responsible for photosynthesis in plants, the process by which sunlight is converted into food energy. To track chlorophyll levels, the CBIBS buoys measure the amount of algae in the water in micrograms per liter (ug/l). This is reported as an hourly average. (Chlorophyll-a is not measured at all CBIBS locations.)
Current direction is the direction on a compass toward which water is moving. For example, a current direction reading of 90° indicates that the current is running toward the east. This is reported as an six-minute average. Current direction is affected by tides, wind, and the shape of the water body.
Current is a movement of water; current speed is the speed of this movement. CBIBS buoys measure current speed in nautical miles per hour, also known as knots. This is reported as a six-minute average.
The amount of oxygen dissolved in Bay waters is a critical measure of habitat quality; without oxygen, living resources die. Dissolved oxygen (DO) is measured in milligrams per liter (mg/l). This is reported as an hourly average. (DO is not measured at all CBIBS locations.)
Salinity is the concentration of salt in the water. Technically, CBIBS buoys measure specific conductance, and then apply a linear formula that lets us report salinity in practical salinity units—PSUs. Salinity levels are a function of the mixing of ocean waters (approximately 32 PSU) with freshwater from the Bay’s tributaries (< 1 PSU). This is reported as an hourly average. Salinity is an important factor in determining where the Bay’s plants and animals live, and in some cases, when the animals reproduce or migrate. In any given location, salinity can vary greatly depending upon river flow, being low during high flows and high during droughts. Most of the Bay’s living resources are adapted to these large swings in salinity, but extreme floods or droughts can lead to stressful conditions. You may see salinity ireported in parts per thousand (ppt) by other systems. PSU and ppt are essentially equivalent in waters in the Chesapeake Bay and North Atlantic.
Sea Nettle Probability
This number is derived from a formula that uses water temperature and salinity to describe your chances of encountering sea nettles at a buoy's location.
Turbidity describes how clear the water is. This is measured using a transmissometer, which records turbidity values in nephelometric turbidity units (NTUs). This is reported as an hourly average. (Turbidity is not measured at all CBIBS locations.) .
Temperature is how hot or cold something is as measured on a definite scale. CBIBS buoys measure water temperature in degrees Celsius and convert this measurement into degrees Fahrenheit. CBIBS buoys report water temperature as a six-minute average.
CBIBS reports the direction the waves are going toward. For example, a wave direction of 90° indicates that the waves are running from west to east. This is reported as a six-minute average.
Wave Height (Significant)
Significant wave height is the average height—from crest to trough—of the highest portion of waves recorded in a given monitoring period at a buoy. Wave measurements are reported by CBIBS buoys every six minutes.
Wave Period (Significant)
Significant wave period is the time that passes between two successive wave crests that move past a buoy. Wave measurements are reported by CBIBS buoys every six minutes.
Wind direction describes the direction on a compass from which the wind comes. For example, a wind direction reading of 90° indicates that the wind is coming from the east. This is an average over the previous six minutes.
Wind gust describes the fastest wind speed recorded. At CBIBS buoys, this is the highest five-second running mean recorded during the previous six-minute period. CBIBS measures wind gust in meters per second (m/s), which is converted into other units for our website and apps—usually knots (nautical miles per hour).
Wind speed describes how fast the air is moving past a certain point at a certain time. CBIBS tracks this as a running mean over the previous six minutes. CBIBS measures wind speed in meters per second (m/s), which is converted into other units for our website an apps, usually knots (nautical miles per hour). Wind speed affects sea state (calm or wavy) as well as the mixing of water in the Bay.