Wind Speed, Direction and Air Temperature Screen Information dialog allows for the input of: Wind Direction (code dd) and Wind Speed (code ff), Dry Bulb (code TTT) and Wet Bulb (code TbTbTb) Temperature and Type of Wet Bulb (code Sw). The Dew Point (code TdTdTd) is then calculated from the input Dry and Wet bulb.

Wind Direction -

Definition: True direction, in degrees, from which the wind is blowing referenced to true north (O degrees T). This is a mean direction averaged over a period of ten minutes.

Method of Measurement: The true wind direction can be determined from the orientation of sea waves or from steaks and foam on sea surface or from the apparent wind observed aboard the ship. If apparent wind is used then the motion of the ship must be removed to obtain true wind. The wind can also be of type variable. The true wind can also be calculated using the Wind Calculator .

Dialog Operation: Select the appropriate radio button depending if the wind direction is variable or determinable. . If the wind direction is determinable input the wind direction into the edit box. If variable is selected then no wind direction is input and code 99 is automatically selected. It is also possible to calculate the wind direction using the Wind Calculator . Click on the Wind Calculator button. Code ff is the wind direction in tens of degrees.

Definition: True wind speed in knots, measured or estimated as indicated by iw

Method of Measurement: Wind speed can be determined by the appearance of the sea surface and the Beaufort scale. Wind speed can also be determined by the anemometer, or the effects of the wind on people or objects on the ship.

Dialog Operation: The wind speed can directly be entered into the edit box. Wind Speed can also be determined from the Beaufort scale. Using the mouse or the up/down arrow keys select a description in the Beaufort scale list box. The associated sea state is shown in the diagram, a detailed description of the sea state is also displayed and code ff is determined. If the wind speed is greater than 64 knots then the wind speed must be manually filled into the edit box. Code ff is the wind speed if the wind speed is less than 99 knots. If the wind speed is greater than 99 knots, code ff is coded with 99 and code fff box should be filled in with appropriated wind speed greater than 99 knots.

All pictures may be viewed simultaneously by clicking the 'Display all Sea State Diagrams' button. Make a selection by clicking on the approriate picture. Click 'Use Values' to return. Code ff is automatically determined with the exceptions mentioned above for wind speeds greater than 64 knots.

Definition: Air temperature to tenths of a degree Celsius. It is the measurement of the heat content of the air.

Method of Measurement: Thermometer of psychrometer. Take the reading on the windward side of the ship being sure to protect thermometer from radiation, precipitation, and spray.

Dialog Operation: The signed dry bulb temperature is recorded in the edit box in Celsius up tenths of a degree. The code TTT is the temperature to tenths of a degree without the decimal point. Sn is the sign.

Definition: Definition: Wet bulb temperature in degrees Celsius. This is that temperature at which water evaporated into the air brings the air to saturation at the same temperature.

Method of Measurement: Psychrometer. The thermometer must be read as soon as possible after ventilation or whirling has stopped. Moisten clean wet bulb muslin on all sides with purest (distilled) water available. If temperature is below 0 degrees C, the muslin wicking should be covered with a thin coating of ice.

Dialog Operation: The signed wet bulb temperature is recorded in Celsius to tenths of a degree and the signed value is input into the edit box. The code TbTbTb is temperature to tenths of a degree without the decimal point. The sign and type of wet bulb is selected from the list box using the mouse or the up down arrow keys. Code Sw automatically selected.

Definition: This is the temperature in Celsius at which condensation will occur causing dew or frost to form. It corresponds to a relative humidity of 100%.

Method of Measurement: It is computed from the wet bulb and dry bulb temperature.

Dialog Operation: It is automatically calculated from the dry and wet bulb.