‰ Now 18 WPM transition file follows ‰

Average daily sunspot numbers and solar flux are down this week.
Average daily sunspot number declined nearly 28 points to 1R7, and
the daily solar flux average was down nearly 7 points to 67R4.  When
the solar flux is less than 70, it often means no sunspots, and the
sunspot number has been zero for a week.  Predicted solar flux for
the next week is 70, which suggests a sunspot or two, with the
chance for sunspots increasing after August 2.  Currently the IMF,
Interplanetary Magnetic Field, points south, making our planet
vulnerable to geomagnetic upset.  The effect from solar wind should
be mild, with the planetary A index for July 27 to 31 predicted at
15, 5, 5, 8 and 15.  Geophysical Institute Prague predicts quiet to
unsettled conditions for July 27, quiet for July 28, quiet to
unsettled July 29, unsettled July 30, quiet to unsettled July 31 and
quiet again on August 1 to 2.  In response to our links to
historical sunspot activity graphs at wm7d.net, Sid Sosin, W7SID of
Bellevue, Washington commented, What data was available on sunspot
activity in 1761 and the remainder of the 18th century, and the 19th
century, for that matter?  Galileo was an early observer and
recorder of sunspots, and you can see his wonderful daily sketches
from the 18th century at the //hsci.cas.ou.edu/exhibits/ web site.
You can even watch animated versions of his drawings, showing the
daily progression of sunspots across the suns earth side face at the
above mentioned link, and at
//galileo.rice.edu/sci/observations/sunspot underscore
drawings.html.  Jim Henderson, KF7E of Queen Creek, Arizona asked
what the lowest recorded solar flux is.  We went over that a couple
of months ago in ARLP022, and the lowest value Ive seen is right
around 65.  Robert Wood, W5AJ of Midland, Texas sent a link to a
picture of the sun and asked about a dark patch near the northern
pole.  I dont know what it is, but I assume it might be a cooler
area, because sunspots are dark and they are cooler relative to
nearby areas.  It sure is a nice picture though.  See it at the
//umbra.nascom.nasa.gov/eit/images/ web site.  The A index is
derived from eight daily readings from magnetometers.  We generally
want to see those numbers low, especially if we are trying to
propagate radio signals over polar paths, because higher geomagnetic
activity signals greater absorption.  But watch over the next few
years as solar activity increases.  Greater solar activity not only
may signal more sunspots, but it also means more solar flares and
solar wind, which often affects earths geomagnetic field.  So
increased sunspot activity is a kind of double edged sword.  We want
more sunspots, but along with that can come greater chances of
geomagnetic storms.  For more information concerning radio
propagation, see the ARRL Technical Information Service at
//www.arrl.org/tis/info/propagation.html.  For a detailed
explanation of the numbers used in this bulletin, see
//www.arrl.org/tis/info/k9la dash prop.html. An archive of past
propagation bulletins is at //www.arrl.org/w1aw/prop/ .  Monthly
propagation charts between four USA regions and twelve overseas
locations are at //www.arrl.org/qst/propcharts/.  Sunspot numbers
for July 19 through 25 were 12, 0, 0, 0, 0, 0 and 0 with a mean of
1R7. 10R7 cm flux was 68R3, 67R3, 66R4, 66R2, 67R2, 68, and 68R6,
with a mean of 67R4. Estimated planetary A indices were 3, 12, 12,
4, 3, 2 and 2 with a mean of 5R4. Estimated mid latitude A indices
were 3, 9, 10, 3, 4, 2 and 2, with a mean of 4R7‚

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