Written by intern Joe Moore, Senior Meteorology student at Millersville University.

As a meteorology student, I know a thing or two about weather. So, I decided to write this handy guide to using a Kestrel to take measurements as a storm spotter. As someone with experience in the SKYWARN program of the National Weather Service, I have made this guide to align with the standards for storm spotting and reporting.

Wind
Applies to: All models (Direction: 4500 only)

To take a wind measurement, you should be in an open area, with 10 times the height of the nearest building away from you. (Eg. if you are near a 2 story home- about 25 feet tall – you should stand 250 feet away) While this is not always possible, it helps to get better measurements. It is also important to take into effect the terrain around you when taking a wind measurement.

Making the measurement with a Kestrel Weather Meter:
For 1000, 2000, 2500, 3000, 3500: You may need to scroll through the list of measurements by using the left and right arrow keys.
For 4000+: You may need to scroll through list of measurements by using the up and down arrow keys.

Instantaneous Wind Speed: This is what is displayed on the Wind Speed screen. For NWS SKYWARN purposes, it is suggested to use either MPH or KTS as units. This is the “live” display of the data.

Wind Gust/Max Wind: This is the maximum 3-second sustained value. Use the left/right arrow keys to get to this value. (Note for 4000+: You need to turn this “on” to record max and avg wind by pressing the enter (horizontal bar) key on the max/avg screen. Do this before you begin reporting!)

Sustained wind speed: Scroll to the left or right to find this value. (For 4000+: this value is on the same screen as the max wind speed). For 1000-3500, this value is the average wind speed since turning on the unit. For 4000+, this is in the average since you have selected to record the value. Note, for NWS standards, averages winds are determined over a 2 minute period.

A note about the impeller on your Kestrel: The impeller on every Kestrel is replaceable. It is suggested to replace at least every battery change (batteries are have a life 300-400 hours of active use, depending on the model). The range of the impeller is 0.8 to 89 MPH for 3% accuracy (NWS requirement is 5%), and it will work up to 135 MPH (with less accuracy).

Temperature
Applies to: All models except 1000

All Kestrel models are equipped with quick-response thermometers that can are externally mounted from the case to give the most accurate reading possible. This patented technology allows you to measure temperature quickly and accurately.

Making the measurement with a Kestrel Weather Meter:
Navigate to the temperature screen (2000-3500: left and right arrows; 4000+: up and down arrows).

For air temperature, wave the Kestrel around for a few minutes. If taking from extreme environments (eg. 78 F in a house to 25 F outside) allow a few minutes for it to adjust. In cold environments, do not breath on the unit nor touch the sensor.

For water temperature, submerge unit in water. All Kestrel units are sealed to IP67 standards, which means it can be submerged at a 3 meter depth for up to 30 minutes. Unless you have goggles, it may be useful to use the hold function (on the 2000/2500/3000/3500) or manually capture the data in the data logger (4000+).

For snow temperature, place Kestrel in snow. As with when taking water measurements, the hold/data capture function of your Kestrel may be useful.

FYI: Water and Snow temperature are usually not useful to NWS Meteorologists, but are interesting parameters to measure. (Snow temperature is used by Olympic skiers and snowboarders to determine how much wax to use on their skis/snowboards.)

Other benefits to Kestrel units to keep you safe
Many Kestrel units can also display things like wind chill (2000+) and heat index (3000+). Barometric Pressure is another useful weather parameter to measure (2500/3500/4000/4500). Kestrel units are designed manufactured in the USA (in Boothwyn, PA) and are designed to be the best portable weather meters in the world! All units come with a 5 year warranty. Even after this period, any unit that stops functioning may be repaired or replaced with an equivalent model for a discount under the Customer Care Program.

***Nielsen-Kellerman, manufacturer of Kestrel Pocket Weather Meters, offers a 15% discount to SKYWARN spotters.***

Be sure to follow us on Twitter.com/KestrelChick and www.facebook.com/KestrelMeters for all the latest on weather, Kestrel meters and giveaways!

Joe Moore is an intern as Kestrel, working with the sales and marketing department this summer. He studies Meteorology at Millersville University with a minor in general business. Through one of his professors, Dr. Richard Clark, and the University Corporation for Atmospheric Research (UCAR), Joe was selected to attend the National Center for Atmospheric Research’s (NCAR) Undergraduate Leadership Workshop in Boulder, CO.

I was very excited to visit NCAR this summer! As a student of meteorology, I knew some things about this giant center for research, but I was really excited when I was selected to attend this workshop. A few facts about NCAR/UCAR:

• UCAR was established by the University community to further the advancement of research in the atmospheric and related sciences
• UCAR created and manages NCAR, which is located across four campuses at and around Boulder, CO
• NCAR/UCAR employ around 1,500 people (including management and support staff)
• NCAR/UCAR is funded mostly through the National Science Foundation
• NCAR scientists research things such as climate change, hurricane development, severe weather warning systems, supercomputers, aircraft-based instrumentation and more!

The NCAR Mesa Lab in Boulder, CO.

During the workshop we attended, our first stop was the NCAR Mesa lab, which was designed by world-famous architect I.M. Pei. The structure can be seen while approaching Boulder, as it sits 600 feet above the city.

NCAR has a very large supercomputing facility to meet the needs of scientists who must run computer models which simulate things in the atmosphere- everything from pollution to severe thunderstorms to the earth’s climate. The Mesa lab also is host to the Visualization Laboratory, which is a high-tech conference room capable of displaying 3D simulations.

The Gulfstream-V, one of two research aircraft used by NCAR, sits in its hanger undergoing preparation for a hurricane research project later this summer.

Another one of the labs I got to visit was the Research Aircraft Facility. We were lucky enough to catch one of the airplanes- the Gulfstream-V- was in the hanger, being prepared for a project called PREDICT which will deploy late this summer to research pre-development of tropical systems in the Atlantic. It was really cool to see scientific research on this scale, with so much coordination between everyone. Many of the instruments they take up on the plane and developed at RAF because a scientist wants to measure a certain atmospheric variable in-flight.

We also visited the National Renewable Energy Laboratory’s National Wind Technology Center. There were many different types of wind turbines being tested, and it was very interesting for me to see how NREL works with industry to develop and market the technologies it develops. In addition to harnessing the power of wind, the facility made use of a large solar array to power its operations.

Of course, it wasn’t all research science at the workshop. We were fortunate enough to be able to take a trip up to Rocky Mountain National Park where we had to walk across some snow to get to a lookout point. It was beautiful and really a treat for someone like me who normally doesn’t see mountains of this size.

Overall, I had a lot of fun at NCAR. I was able to meet my peers at other institutions and also meet some of the top atmospheric scientists in the world! While I’m back at Kestrel now for the rest of the summer, I was able to make some great connections at NCAR and I hope our paths cross again in the future.

For more information about the NCAR Undergraduate Leadership Workshop, check out the workshop page at NCAR’s website. You can find out more about NCAR and UCAR at their websites.

Wondering about weather words? Check out the Kestrel weather glossary online.

Written and researched by Kestrel intern Joe Moore, Senior Meteorology student at Millersville University.

Heat index and wind chill are two of the most popular “apparent temperature” indexes which try to convey a more useful temperature to the general public. Most people understand the basic premise of these indexes (wind makes cold temperatures feel even colder, humidity makes it feel hotter), but did you know that because of how heat index was developed, the heat index can be lower than the actual air temperature?

Heat index was developed by R. G. Steadman in a 1979 paper published in the Journal of Applied Meteorology titled, “The Assessment of Sultriness. Part I: A Temperature-Humidity Index Based on Human Physiology and Clothing Science.” As a researcher in the Textiles and Clothing Department at Colorado State University, his paper takes into account a number of factors to form what we know today as the Heat Index. These factors that Steadman accounted for include include:

• “Basic Dimensions” – A typical human, either sex, height of 1.7m (5’ 5.8”), 67kg (147.7lbs), which gives a person’s surface area of 1.78 square meters (19.1 square feet)
• “Effective radiation area” – The amount of radiation exchange between radiant heat and surroundings. Steadman uses the average ratio of 0.79 for clothed parts of the body, and 0.85 for bare (unclothed) parts under mild conditions.
• “Clothing cover” – The amount of clothing and the thickness of the clothing, which is assumed to be “long trousers and a short-sleeved shirt of blouse” to cover 84% of the body’s surface. While there can be differences in the exact apparel worn along with hair length, Steadman points out that these effects impacts are similar to individual variations in skin insulation.
• “Core temperature” – The comfortable body temperature (which the body is trying to achieve in equilibrium) is 37 C (98.6 F).
• “Activity” – The amount of actively a person in engaged in. Steadman uses a person walking at a rate of 1.4m/s (3.1 mph), which generates 800 W/m^2 of energy from the human body.
• “Effective wind speed” – This is the wind speed on the body. Meteorologists measure wind speed (Eg. At your local airport) at a height of 10 meters (33 feet). Using the average wind speed at 10 meters, and factoring in the diminished winds that actually reach the surface, Steadman uses an effective wind speed of 1.32 m/s (3 mph).
• “Ventilation rate” – The amount of heat exhaled by a person. For summer conditions, this is estimated to be about 8% of heat from the body lost through the lungs.
• “Skin resistance to moisture transfer” – What most people would call the effect of humidity on the skin.
• “Clothing resistance to heat transfer” – The amount of heat not escaping through garments.
• Along with a few other complex factors

Heat Index Chart (Courtesy National Weather Service)

It is important to note that there is no “official” formula to calculate heat index exactly. This is because heat index is a value from a table. Your Kestrel unit looks up the table value using a complex polynomial equation that gives a very accurate value from the table. This is why, if you use the temperature and dew point from the Kestrel and plug it in to some online calculators, you may see a difference in the heat index value. Rest assured, your Kestrel unit is using the most accurate method possible. (Most online calculators of Heat Index, such as this one on the national weather service website, use a modified formula which carries an error of +/- 1.3F. The Kestrel uses a much more sophisticated formula that is nearly identical to the index table.)

(From top to bottom) Temperature, Relative Humidity and Heat Index. Notice the Heat Index is less than the air temperature. Is that right?!

Looking at the official chart (or at your Kestrel indoors) you notice what seems to be an anomaly-the heat index may be lower than the current temperature. I noticed it this morning on the Kestrel meter I use at my desk. (See image on the right.)

The reason for this is that the index assumes a small amount of wind, and also assumes the person is walking. Note, the amount of wind and the walking speed (defined as “Activity” in the list above) is a constant value throughout the table. So in many low-humidity situations (under 30% humidity) with an air temperature of less than 98 F, the heat index will always be lower than the actual air temperature, as explained above. In the US, this can be common in desert areas that are very dry such as places in Arizona, New Mexico and Nevada.

For more information about Heat Index, check out this great resource from the National Weather Service: http://www.srh.noaa.gov/jetstream//global/hi.htm

To learn more about humidity and other environmental conditions that your Kestrel meter measures, check out Knowledge Center.