Climate Narrative for Rhea County, Tennessee




Дата канвертавання26.04.2016
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Climate Narrative for Rhea County, Tennessee.
Prepared by the Natural Resources Conservation Service National Water and Climate Center, Portland, Oregon.
Climate Tables are created from climate station Dayton, Tennessee.
Thunderstorm days, relative humidity, percent sunshine, and wind information are estimated from First Order station Chattanooga, Tennessee.
Table 1 gives data on temperature and precipitation for the survey area as recorded at Dayton in the period 1961 to 1990. Table 2 shows probable dates of the first freeze in fall and the last freeze in spring. Table 3 provides data on the length of the growing season.
In winter, the average temperature is 39.4 degrees F and the average daily minimum temperature is 29.0 degrees. The lowest temperature on record, which occurred at Dayton on January 21, 1985, was -15 degrees. In summer, the average temperature is 75.6 degrees and the average daily maximum temperature is 87.7 degrees. The highest temperature, which occurred at Dayton on July 16, 1980, was 107 degrees.
Growing degree days are shown in Table 1. They are equivalent to "heat units". During the month, growing degree days accumulate by the amount that the average temperature each day exceeds a base temperature (50 degrees F). The normal monthly accumulation is used to schedule single or successive plantings of a crop between the last freeze in spring and the first freeze in fall.
The average annual total precipitation is about 56.31 inches. Of this, about 29.87 inches, or 53 percent, usually falls in April through October. The growing season for most crops falls within this period. The heaviest 1-day rainfall during the period of record was 5.94 inches at Dayton on December 30, 1969. Thunderstorms occur on about 56 days each year, and most occur between May and August.
The average seasonal snowfall is 5.9 inches. The greatest snow depth at any one time during the period of record was 10 inches recorded on February 13, 1960. On an average, 4 days per year have at least 1 inch of snow on the ground. The heaviest 1-day snowfall on record was 9.6 inches recorded on February 13, 1960.
The average relative humidity in mid-afternoon is about 55 percent. Humidity is higher at night, and the average at dawn is about 85 percent. The sun shines 64 percent of the time in summer and 47 percent in winter. The prevailing wind is from the south. Average wind speed is highest, around 8 miles per hour, in February through April.

TABLE 1.--TEMPERATURE AND PRECIPITATION
(Recorded in the period 1961-90 at DAYTON, TN2360)
| |

| Temperature | Precipitation

| | _

| | | | 2 years in | | |2 years in 10| |

Month | | | | 10 will have-- | Average | | will have-- | Average |Average

|Average|Average|Average| Maximum | Minimum |number of|Average| | |number of|snowfall

| daily | daily | |temperature|temperature| growing | | Less | More |days with|

|maximum|minimum| | higher | lower | degree | |than--|than--|0.10 inch|

| | | | than-- | than-- | days* | | | | or more |

| | | | | | | | | | |

| 0F | 0F | 0F | 0F | 0F | Units | In | In | In | | In

| | | | | | | | | | |

January-----| 46.9 | 26.7 | 36.8 | 68 | -3 | 12 | 4.83 | 2.91| 6.56| 8 | 2.7

| | | | | | | | | | |

February----| 52.5 | 29.8 | 41.1 | 75 | 5 | 29 | 4.83 | 2.70| 6.71| 7 | 1.6

| | | | | | | | | | |

March-------| 62.9 | 37.7 | 50.3 | 83 | 15 | 119 | 6.36 | 3.70| 8.74| 8 | 0.4

| | | | | | | | | | |

April-------| 72.8 | 45.1 | 59.0 | 89 | 25 | 284 | 4.54 | 2.61| 6.26| 7 | 0.1

| | | | | | | | | | |

May---------| 79.6 | 53.3 | 66.5 | 91 | 34 | 509 | 5.18 | 3.13| 7.01| 8 | 0.0

| | | | | | | | | | |

June--------| 86.4 | 61.0 | 73.7 | 97 | 45 | 712 | 3.63 | 1.90| 5.15| 6 | 0.0

| | | | | | | | | | |

July--------| 88.8 | 65.0 | 76.9 | 99 | 45 | 825 | 4.74 | 2.67| 6.57| 8 | 0.0

| | | | | | | | | | |

August------| 88.0 | 64.3 | 76.2 | 97 | 52 | 804 | 4.14 | 2.05| 5.96| 6 | 0.0

| | | | | | | | | | |

September---| 82.2 | 58.6 | 70.4 | 94 | 39 | 612 | 4.25 | 1.95| 6.22| 6 | 0.0

| | | | | | | | | | |

October-----| 72.2 | 46.2 | 59.2 | 86 | 27 | 297 | 3.39 | 1.72| 5.07| 4 | 0.0

| | | | | | | | | | |

November----| 60.4 | 38.2 | 49.3 | 78 | 16 | 96 | 4.74 | 3.19| 6.16| 7 | 0.0

| | | | | | | | | | |

December----| 50.3 | 30.5 | 40.4 | 71 | 5 | 27 | 5.67 | 2.80| 8.17| 7 | 0.9

| | | | | | | | | | |

| | | | | | | | | | |

Yearly: | | | | | | | | | | |

| | | | | | | | | | |

Average---| 70.2 | 46.4 | 58.3 | --- | --- | --- | --- | ---| ---| --- | ---

| | | | | | | | | | |

Extreme---| 107 | -15 | --- | 100 | -4 | --- | --- | ---| ---| --- | ---

| | | | | | | | | | |

Total-----| --- | --- | --- | --- | --- | 4325 | 56.31 | 47.22| 64.17| 82 | 5.9

| | | | | | | | | | |
* A growing degree day is a unit of heat available for plant growth. It can be calculated by adding the maximum and minumum daily temperatures, dividing the sum by 2, and subtracting the temperature below which growth is minimal for the principal crops in the area (50 degrees. F)



TABLE 2.--FREEZE DATES IN SPRING AND FALL
(Recorded in the period 1961-90 at DAYTON, TN2360)
|

| Temperature

|

| _

Probability | | |

| 24 0F | 28 0F | 32 0F

| or lower | or lower | or lower

| | |

| | |

Last freezing | | |

temperature | | |

in spring: | | |

| | |

1 year in 10 | | |

later than-- | April 5 | April 15 | April 25

| | |

2 year in 10 | | |

later than-- | March 29 | April 10 | April 20

| | |

5 year in 10 | | |

later than-- | March 17 | March 31 | April 11

| | |

First freezing | | |

temperature | | |

in fall: | | |

| | |

1 yr in 10 | | |

earlier than-- | November 2| October 21| October 7

| | |

2 yr in 10 | | |

earlier than-- |November 7 | October 26| October 12

| | |

5 yr in 10 | | |

earlier than-- |November 16 | November 6| October 23

| | |

| | |


TABLE 3.--GROWING SEASON
(Recorded for the period 1961-90 at DAYTON, TN2360)
|

| Daily Minimum Temperature

| During growing season

| _

Probability | | |

| Higher | Higher | Higher

| than | than | than

| 24 0F | 28 0F | 32 0F

| | |

| Days | Days | Days

| | |

9 years in 10 | 222 | 199 | 173

| | |

8 years in 10 | 229 | 206 | 180

| | |

5 years in 10 | 243 | 218 | 193

| | |

2 years in 10 | 257 | 231 | 205

| | |

1 year in 10 | 264 | 238 | 212

| | |


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