The Doppler Weather Radar Has Evolved
Author: MIKE SELVON
The first Doppler weather radar was commissioned in 1964 by the National Oceanic and Atmospheric Administration, or NOAA. When scientists experimented with tornados, they quickly realized the 3-cm Doppler was not big or powerful enough to receive and track all of the needed information. They realized this one radar would need improvements.
The National Severe Storms Laboratory (NSSL) observed NOAA’s upgraded 10-cm Doppler in 1973, which was able to track a tornado’s life cycle. This data told scientists of the circular motion of a tornado’s winds, as well as the centripetal point of rotation, which the inner clouds rotate around.
Scientists sought to increase their knowledge of how storms like these formed. One particular storm in May of 1973 cut right through the heart of Union City, Oklahoma. Union City lies in the center of the infamous “Tornado Alley” region of the United States. With the data received by the scientists, they were able to start planning upgrades and improvements of the Doppler weather radar so it could be a more reliable asset to the government and the residents.
The Doppler system maps weather radar by measuring the motion inside these very hostile storms. Over time, scientists discovered that tornadoes produce a unique signature; different from regular storms. And as time went on, they were able to recognize this pattern, which they later called the “tornadic vortex” signature.
Doppler weather radar improvements, including NEXRAD (Next Generation Radar), increased the warning time and the path prediction accuracy in storms with tornadic activity. Using NEXRAD, scientists nationwide are able to share data, giving a clearer picture of what to expect. In 2007, the National Weather Service picked up on tornadic cloud rotation and signature “hook-echo” patterns.
Residents of Enterprise, Alabama were warned to take cover, and a full eighteen minutes later the tornado touched ground. Thanks to NEXRAD, the previous, typical five minute warning time to get to a safe place finally saw a dramatic increase.
Eighteen minutes is ample time to gather family and emergency supplies and take shelter. It was also enough time for some commuters to seek shelter in a sturdy building and get off the streets. It is the goal of all meteorologists to increase the lead time to 20 minutes, saving many more lives in the process.
Doppler weather radar has come a long way. In the beginning, scientists hoped to save lives by getting the severe weather reports announced faster. Now, almost forty-five years since its birth, this one radar system is doing exactly that.
Locating The Wind
Author: Dave Bello
Knowing the direction of the wind is one of the most important aspects of sailing properly and safely. Trimming sails correctly, identifying points of sail, and executing procedures such as man-over-board and heaving-to, for example, all require knowing the direction of the wind. Yet, many beginners find it very difficult to find the source of the wind direction. Moreover, even when they do find the correct wind direction, it is a very time consuming process.
This article describes typical mistakes made by beginning sailors and then introduces a simple and reliable method to find the direction of the wind quickly while sailing. The observations and suggestions in this article were generated during the sailing lessons taught at Fair Wind Sailing School.
Common Mistakes
Beginning sailors typically make two common mistakes when attempting to identify the wind direction. The first is to stare at the wind instruments and solely rely on the instruments to reveal the source of the wind. While instruments can be a valuable aid to navigation, prior to the development of basic sailing skills are developed, they can often be confusing and even misleading.
Our experience has been that the wind instrument is usually the worst place to find the wind direction for a beginning sailor. First, reading a wind instrument may not be intuitive to the new sailor. It is quite common for new sailors to misread the instrument confusing true versus apparent wind or even misreading the directional arrow of an analog wind gauge. Even more concerning is that — as any experienced sailor will testify — wind instruments are typically wrong. Calibration issues, slow response times, shifting winds and knowing how to switch between true and apparent readings all contribute to wind accuracy readings that are far too often different from the actual conditions. This is especially true for lower cost wind instruments.
Even if the wind instrument is reading correctly, it can take the beginning sailor a long time staring at the wind instrument to read it correctly. While staring at the instrument, the helmsman is not looking out. It is quite common, again particularly for a beginner, to turn the boat when not looking ahead. As the helmsman unknowingly turns the boat, the direction of the wind appears to turn too. Of course, this is not the true weather conditions, and it further complicates the first challenge of finding the direction of the wind.
When taken in combination, the issues of long periods of staring the electronics rather than sailing the boat, slow responses to shifting wind and potential mis-calibrations, the wind instrument is quite possibly the worst way to try and find the wind direction quickly for the beginning sailor.
The mast head fly is a step better than the wind instrument. Since it always reads the apparent wind, the mast head fly eliminates one of the issues inherent with wind instruments, like figuring out if you are looking at true or apparent wind. However, looking up at the mast head to quickly identify prevailing wind direction is also difficult for new sailors. Similar to staring at wind instruments, long periods looking straight up at the top of the mast make steering a boat straight very difficult for newcomers. Again just like looking at the wind instrument for long periods, what appears to be a shifting wind can be nothing more than the boat turning. In summary, while better than the wind instrument, reading the wind direction quickly from the mast head fly can be a trickly and time consuming endeavor the new sailor.
A third common mistake for beginners is to over think the situation. Typically, this occurs with confusion between true and apparent wind and trying to estimate one from the other. When starting out, newcomers can simplify the situation by remembering that we feel only the apparent wind. Since we also trim sails and run the boat to apparent wind, this is the only wind data point we need. It is the apparent wind, then, that we are looking for and that we can feel. For the beginner, focus on the apparent wind and forget the true wind to simply observations and speed you decision making.
A Simple and Easy Method To Identify Wind Direction
To identify the wind direction, we need a method to avoid the common mistakes. This means first of all, ignoring the instruments. Instead, we will identify the wind direction the old fashion way — we will feel it. To feel the wind, we will also need minimal distraction. We accomplish this by closing our eyes, too! It may sound counter-intuitive to close your eyes when steering a sail boat, but we will only need a second or two with this procedure, and closing your eyes for a second or two is far better than staring at instruments for long periods.
The total procedure is very simple, close your eyes, feel the wind on your cheeks and turn your head until you are looking directly into the wind. You’ll be amazed that in a second or two you’ll be able identify the wind direction accurately nearly 100% of the time. Fast and accurate — exactly the procedure we are looking for!
Summary
In summary, to accurately and quickly identify the wind direction, ignore the instruments and use your senses. By closing your eyes and feeling the wind on your face, you’ll be able to quickly and accurately identify the wind direction nearly 100% of the time in seconds.
