The Gross Lift minus the Average Weight of the balloon = The negative weight of the filled balloon

The two primary gasses are:
Helium (He) and Hydrogen (H2)

Near space is that region of the atmosphere above 60,000 feet but below the accepted altitude of space, 328,000 feet.

Amateur radio (also called ham radio) is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication. The term "amateur" is used to specify persons interested in radio technique solely with a personal aim and without direct pecuniary interest, and to differentiate it from commercial broadcasting, public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.). The amateur radio service (amateur service and amateur satellite service) is established by the International Telecommunication Union (ITU) through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with an identifying call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics and the host government's radio regulations. Radio amateurs use a variety of voice, text, image, and data communications modes and have access to frequency allocations throughout the RF spectrum to enable communication across a city, region, country, continent, the world, or even into space. Amateur radio is officially represented and coordinated by the International Amateur Radio Union (IARU), which is organized in three regions and has as its members the national amateur radio societies which exist in most countries. According to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are regularly involved with amateur radio.[1] About 830,000 amateur radio stations are located in IARU Region 2 (the Americas) followed by IARU Region 3 (South and East Asia and the Pacific Ocean) with about 750,000 stations. A significantly smaller number, about 400,000, are located in IARU Region 1 (Europe, Middle East, CIS, Africa).

More at; http://en.wikipedia.org/wiki/Amateur_radio

Great Plains Super Launch the annual convention of HAB enthusiasts. Check out http://superlaunch.org for more details.

Science, Technology, Engineering, Math

The gas surrounding the earth, held by gravity, comprised of nitrogen, oxygen, and other gasses.

The lowest layer of the atmosphere, extending from the surface to between 4-11 miles (6.4-17.7 km) high, depending on latitude. Containing approximately 75% of the atmosphere by mass, it is characterized by generally decreasing temperatures with increasing altitude.

American Radio Relay League -- The National Association for Amateur Radio

National Aeronautics and Space Administration. See www.nasa.gov.

Global Positioning System; a constellation of satellites that provide the information necessary to receivers to calculate the latitude, longitude, and altitude of the receiving antenna.

Automatic Packet Reporting System

Federal Aviation Regulations Part 101; the regulation document that defines the legal operation of high-altitude balloons (referred to as unmanned free balloons in the regulations) in the United States national airspace system.

AX.25 is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. The protocol used for packet radio (and therefore APRS).

MODulator/DEModulator -

There is no clear legal definition for what is considered payload. The most conservative approach (when calculating payload weight, for example) is to include anything that isn't the balloon. However, some teams do not include the recovery systems (parachute and lines) in the weight calculations. Colloquially, the payload is comprised of the system(s) being lifted to high altitude, including tracking systems, experiments, etc.

Amateur Radio High Altitude Ballooning

The ascent rate is how fast usually in feet per minute the balloon rises. It depends on the weight of the balloon, nozzle lift, payload weight and parachute weight.
A good simple calculator is on the Near Space Ventures web site at; http://nearspaceventures.com/cgi-bin/ascent.pl

The speed (usually in ft/min) that the payload is falling, usually after burst. Depends on the combination of payload weight and parachute size, and changes through the descent: at the apex of the flight, the atmosphere is not dense enough to slow the parachute to the final rate, so the rate slows as the payload nears the surface.

The maximum volume of gas contained by the balloon. This is a specification usually provided by the manufacturer (though sometimes listed as "Diameter at Burst"), and determines the maximum altitude that can be achieved by a specific balloon given a specific payload weight.

Generically defined as any data collected remotely and transmitted to another location; specifically, the location and sensor data that is sent to the ground from the payload of a balloon. The complexity and speed of the telemetry that is being used defines the amount of bandwidth required in the communications link.

The Wikipedia defines it as:
An amateur radio contact, more commonly referred to as simply a "contact", is an exchange of information between two amateur radio stations. The exchange usually consists of an initial call, a response by another amateur radio operator at an amateur radio station, and possibly a signal report. A contact is often referred to by the Q code QSO. It is often limited to just a minimal exchange of such station IDs. Stations who have made a contact are said to have worked each other. An operator may also say that he has worked a certain country. Amateurs use the slang expression ragchew or ragchewing to refer to an extended, informal conversation, a variation of the common idioms "chewing the fat" and "chewing the rag".[1][2] Sometimes, a contact in person, between two ham radio operators, is humorously referred to as an "eyeball QSO".

The device used to slow the descent of the rest of the payload. Usually attached betwen the balloon and the rest of the payload.

A website used to track the position of an APRS payload as reported to the APRS-IS servers. If looking for a specific payload, the format for the URL is map.findu.com/callsign-ssid (e.g. http://map.findu.com/k6rpt-11).

An amazing google maps based APRS site, with a number of features built in. Very user friendly, this site is good for recommeding to non-technical participants who what to follow your flight online. Format for tracking a specific station is aprs.fi/callsign-ssid (e.g. http://aprs.fi/k6rpt-11).

Bill Brown (WB8ELK) the father of Amateur Radio High Altitude Ballooning.

Bill Brown (WB8ELK) the father of Amateur Radio High Altitude Ballooning.

The coordinate system used to define the position of any point on the Earth's surface north or south of the equator (latitude) and east or west of the meridian line running through Greenwich, England (longitude).

They're more like rectangles and are just a way of dividing up the surface of the Earth. Grid squares are a shorthand means of describing your general location anywhere on the Earth in a manner that is easy to communicate over the air.
Here is a link to a good Grid Square calculator and mapping program.

The area in the atmosphere that contains the highest concentration of ozone (O3), generally located at altitudes of 12-19 miles above the surface. The concentration and altitude boundaries vary throughout the year and depending on location.

Causes skin cancer, and also degrades the natural latex used in the construction of weather balloons; assumed to be a major limit on the ability to achieve extremely long-duration floating missions with latex balloons.

Ionizing radiation (highly-energetic particles) originating in space.

The essential payloads are an APRS tracking beacon and an independent DF beacon to help you find the payload after it lands. Beyond that, anything goes. If you get a data logger, all you need is sensors for what you want to measure in flight, and then just download the data to a computer. Many folks also fly cameras and DVRs, such as a Canon Power Shot with CHDK intervalometer scripts or the GoPro.

Unless you provide your own I-gates, in the United States it's best to put your APRS beacon on the 144.390 MHz the APRS backbone. But more and more areas are also using 144.360Mhz.

That's where a crossband or simplex repeater payload comes in handy. It will have great coverage in the air, but you'd better have your tracking team near the landing site once it lands. You can also arrange to put one tracker in a high spot where he can hear the other trackers and still hit a repeater.

The two primary Internet based sites are:
http://habhub.org/predict/
and
http://nearspaceventures.com/w3Baltrak/readyget.pl

PBC is the thrashing that a balloon package goes through after burst.
The balloon is history (except for shards), and PBC is more closely associated with a combination of parachute instability
(oscillation) and high-drag payloads that unload the parachute riser. Balloon shards remaining attached to the parachute can also destabilize it.

Here is an excellent beginners guide:
http://www.edgeresearchlab.org/contact-us/getting-started/

Actually the long easterly tracks for winter flights are a result of high altitude winds above 50K feet. In the spring and fall these winds do a 180 and change direction. Exactly when this happens is a function mostly of your latitude (distance from the equator). If you look at: http://www.eoss.org/onlinepubs/turnaround/turn_around_winds.htm You will see some graphs for various latitudes in the northern hemisphere. The full data for "Mean Zonal Winds" is linked at the bottom of the page so you can generate this info for yourself at any latitude.