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Answer: In some parts of the world, there are well-defined wet and dry seasons and in some cases people like to keep their rain statistics by resetting seasonal or yearly rain totals to zero at the beginning of, say, July or October. However, in our state precipitation is, on average, fairly evenly distributed throughout the year. That being the case, you would probably want to set your "rain season" to begin on January 1st and end December 31st, so that you can easily check "calendar year" progress, and so rainfall for the year will reset to zero as the next calendar year begins.
Oct. 6, 2009 | Tags: instruments, rain

Answer: The second part of your question is pretty easy to answer, as it isn't extremely unusual to have a day here and there when the entire state is free of cloud cover, with bright blue skies all around. This usually results from a large cool season high pressure system moving across the region. On the other hand, large storm systems can occasionally produce clouds and precipitation covering a majority of the state. However, even in these situations there are often some gaps in the precipitation coverage at any one time, and it would be rather difficult to verify that any particular day in history featured rain everywhere in our state, and all at the same time.
Oct. 5, 2009 | Tags: general meteorology, rain

Answer: Most consumer dial and liquid-in-glass thermometers have a top range around 120 degrees F. What you might try instead could be an electronic stem-type thermometer or digital min/max thermometer, which often have upper ranges of 150 - 350 degrees F. They are available from a number of sources on the web, including some of the weather instrument supply sites and some general retailers. Note that any air temperature measurement should be taken with the thermometer in the shade, and not with the sun shining on it.
Oct. 4, 2009 | Tags: heat, instruments

Answer: While it doesn't happen very often, it is possible. Hurricanes that weaken to tropical depression intensity usually do so because they have encountered disruptive vertical wind shear or moved over cooler ocean waters when they are at sea, or because of the combination of loss of warmth and moisture from below and increased surface friction upon moving over land. If the weakened circulation moves into a more favorable location (off of land and back to sea, or over warmer waters and/or an area of weaker vertical shear) it can potentially regain tropical storm or hurricane strength.
Oct. 3, 2009 | Tags: hurricanes

Answer: The official dates that the Atlantic hurricane season starts and ends are June 1st and November 30th, respectively. That time frame encompasses the part of the year that historically produces the great majority of tropical cyclones, with the peak of the season stretching from around the middle of August through mid-October. It is worth noting, however, that there are rare occurrences of tropical storms and hurricanes that fall outside this "official" season.
Oct. 2, 2009 | Tags: hurricanes

Answer: The "normal" annual rainfall is just an average over a defined time period, that being the 30 years ending with the most recent "zero" year, and updated every ten years. Based on observed totals from the current "climate normals" period of 1971-2000 at RDU, the average yearly precipitation is 43.1 inches, and the standard deviation about that value is plus or minus 6.4 inches. This indicates that annual rainfall ranges between roughly 37 and 49 inches about 67% of the time, and between 31 and 55 inches about 95% of the time.
Oct. 1, 2009 | Tags: drought, rain, records/extremes, water resources

Answer: When sea water evaporates, nearly all the dissolved salt is left behind in the ocean, so that the rain produced by a hurricane is essentially fresh, although there can be some slight exceptions due to entrainment of salt water droplets scoured from the ocean surface by high winds and either blown directly onto land areas or carried up into some of the rain-producing clouds. To illustrate this, if you allow some sea water to evaporate from a dish or glass, you'll see that a crust of salt is left behind.
Sep. 30, 2009 | Tags: hurricanes, rain

Answer: There are a lot of influences on rain drop size and the distribution of sizes in a given rain event. Some of the more notable factors are the intensity of upward motions in the cloud, the relative humidity and degree of supersaturation available there, the concentration and quality of condensation and/or ice nuclei in the vicinity, and the temperature profile of the air within which the drops are forming. The size of droplets reaching the ground also depends on the temperature and relative humidity of the intervening air between the cloud base and the surface.
Sep. 29, 2009 | Tags: general meteorology, rain

Answer: There are several addresses where you can hunt up rain gauge reports from multiple official and unofficial sites around Wake County. For example, you can go to www.nc-climate.ncsu.edu/cronos and type "Wake" in the search box, then click on the name of any station for more details. For a sizable listing of nearby "personal weather stations," go to www.wunderground.com, type a Wake County town into the search form and click "Go," and scroll to the bottom of the resulting page. For a more graphical rain depiction based on a combination of radar and gauges, see water.weather.gov, click on the "NWS WFOs" button below the map, and select "Raleigh, NC (RAH)." You can then turn on/off county lines, highways, etc and can view rainfall amounts, departures from normal and more over varying time frames.
Sep. 28, 2009 | Tags: cool sites, past weather, rain

Answer: This is pretty speculative, since it isn't obvious whether you are asking about the appearance of the sky during the storm or after it cleared up later, or whether you observed a constant glow or something that was intermittent. Sometimes during heavy storms failing transformers and arcing power lines can produce intermittent flashes or periods of blue, green or purple light in the sky. Perhaps more likely you are referring to night skies after the storm, in which case you may have observed an aurora that colored the morning sky.
Sep. 27, 2009 | Tags: astronomy, atmospheric optics, winter weather