UpLift-1 Facts and Figures 28th Dec 2011 Pt-3
Time for some SCIENCE. I have cleaned up all the data from the flight removing duplicated figures and out of place data that sometimes occurs from having lots of receiving stations all trying to add it to the database. The figures are certainly interesting and even fun to see what is going on during the flight.
Wind Speed at Altitude
We all know what the weather is like in our own countries and the news and documentaries will often let you know about other countries. I live in Australia on the SE coast. For my high altitude balloon flight I traveled to the centre of my state (New South Wales – NSW) for a number of reasons. Predominantly it was because of the prevailing winds and the flat open farmland. Easier to ensure a clean landing with few trees and no mountains to have to climb. When I say prevailing winds, I am talking about those at all altitudes that my balloon will be passing through. I mentioned that in previous posts that I use a balloon prediction site and that I get a good idea of wind speeds and thus the direction of the flight. The site even outputs the file as a kml file that can easily be opened by Google Earth.
We can easily use the weather service for the ground winds, but the upper level winds can be a bit fickle and not easily forecast by the prediction service, but the balloon does not stay in those regions too long. The main winds that will govern most of the flight as my latitude (-33 degrees – south of the equator) are those of the jet stream.
Jet Streams (from Wikipedia):
Jet streams are fast flowing, narrow air currents found in the atmospheres of some planets, including Earth. The main jet streams are located near the tropopause, the transition between the troposphere (where temperature decreases with altitude) and the stratosphere (where temperature increases with altitude).The major jet streams on Earth are westerly winds (flowing west to east). Their paths typically have a meandering shape; jet streams may start, stop, split into two or more parts, combine into one stream, or flow in various directions including the opposite direction of most of the jet. The strongest jet streams are the Polar jets, at around 7–12 km (23,000–39,000 ft) above sea level, and the higher and somewhat weaker Subtropical jets at around 10–16 km (33,000–52,000 ft). The Northern Hemisphere and the Southern Hemisphere each have both a polar jet and a subtropical jet. The northern hemisphere polar jet flows over the middle to northern latitudes of North America, Europe, and Asia and their intervening oceans, while the southern hemisphere polar jet mostly circles Antarctica all year round. Jet streams are caused by a combination of a planet’s rotation on its axis and atmospheric heating (by solar radiation and, on some planets other than Earth, internal heat). Jet streams form near boundaries of adjacent air masses with significant differences in temperature, such as the polar region and the warmer air towards the equator.
So what did we find? The following charts shows the balloon flight right up to burst point and also from burst point to landing. It shows the wind strengths that it encountered in kilometers per hour. For reference 40km per hour = 25 miles per hour. Altitude is in meters and similarly 10,000m = 6.2 miles. The chart showing descent should be similar but the rate of fall is exponential and not linear so there will be some compression and expansion of the horizontal axis. Due to the fall taking 1/3 the time of the climb there will be fewer plot points and also a greater potential for GPS inaccuracy.
In the chart below I have labelled the major points of change in the chart. Of interest there were three layers of wind prior to the balloon entering the jet stream or streams. The major point of interest was that there were two jet streams both traveling in the same directions. The winds of the troposphere were approximately half of the strength of the jet streams and in the opposite direction by chance. If the balloon had made it to higher levels in the troposphere, it may have encountered other wind directions, but the winds may have been much lower in strength.
Air Pressure and Altitude
The chart below shows plot points and both altitude and air pressure in Pascals. Pascals for those in non metric countries are defined in Wikipedia as:
The pascal (symbol: Pa) is the SI derived unit of pressure, internal pressure, stress, Young’s modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre. In everyday life, the pascal is perhaps best known from meteorological barometric pressure reports, where it occurs in the form of hectopascals (1 hPa ≡ 100 Pa) or kilopascals (1 kPa ≡ 1000 Pa). In other contexts, the kilopascal is commonly used, for example on bicycle tire labels. One hectopascal corresponds to about 0.1% of atmospheric pressure slightly above sea level; one kilopascal is about 1% of atmospheric pressure. One hectopascal is equivalent to one millibar; one standard atmosphere is exactly equal to 101.325 kPa or 1013.25 hPa or 101325 Pa.
Simply at sea level there will be 100,000 Pascals (left side of graph and the start of the plot from the balloon). Air pressure (Pa) is plotted in red and altitude (m) in blue. The rate of climb is near linear while air pressure is more exponential. Note that the initial rate of climb on the left corner is high as it appears that we were in a thermal or rising air mass.
That concludes the science breakdown of the flight. there are plenty of more breakdowns of the data that can be carried out, but in this and the previous 2 posts I have explored most of the more relevant information that can be derived from the flight. My next post will provide access to the data from the flight.