8. Other atmospheric phenomena
8.3. Reflection of solar radiation and whiteout conditions
Glaze, hoarfrost, and rime are the types of ice accretion (glassy, crystalline, and snowy) that appear on the surface of structures and on wires. Their appearance is glassy, crystalline, or snow-like. Observations of these ice types are carried out with a glaze measuring device according to the standard program as specified by the manual, "Instructions for hydrometeorological stations and posts"[45]. The diameter and weight of accreted ice are measured. The diameter of the sample is determined using a vernier caliper to an accuracy of 1 millimeter. The diameter of the wire (6 millimeters) is taken into account in the results of the calculation. The mass is defined by the volume of melted sample, which was taken from a 25 centimeter length of the wire. The result is then expressed as effective accretion on 1 meter long wire in units of grams per meter. Glaze and hoarfrost accretion data have been taken from the KM-4 observation books for the present analysis and cover the 20-year period from 1966 through 1985.
Among these phenomena, glaze is the most important for producing hazardous conditions. The icing itself is the dangerous event. The formation of glaze in the Arctic during the warm part of the year is due to passage of cold atmospheric fronts and their occlusions. During the autumn and winter, glaze forms during the passage of warm fronts. During the summer, the passage of cold fronts can result in air temperature decreases to 0 degrees Celsius and below, and if there is rainfall glaze forms. In the autumn, glaze can form as a result of the passage of a warm front (cyclone from the south) when rain falls on the cold underlying surface, as well as on masts, wires, and buildings. For example, on Cape Zhelaniya a glaze 26 millimeters in diameter formed on the measuring device during 1 September 1980. It was caused by a warm front in a cyclone whose center was in the Kara Sea whose minimum atmospheric pressure was 985 millibar. When wind was from the south, rain fell at the forward edge of the front where the air temperature was -1 degrees Celsius.
Air temperature exerts a direct influence on glaze formation. When air temperature rises, the density of the accreted ice increases and porosity decreases and vice versa. Glaze forms when air temperature varies over the range from 0 degrees Celsius to -5 degrees Celsius (Figure 48). But some cases of glaze formation have been observed when the air temperature was between -6 degrees and -8 degrees Celsius.
Figure 48. Relative frequency (%) of glaze (1) and hoarfrost or rime (2) versus air temperature.
Hoarfrost forms when the air temperature is -5 degrees Celsius or below. In this case, water vapor freezes more quickly and if the air is not dispersed, air bubbles remain included between the crystals, the accretion surface becomes roughened with discrete bumps, and granular frost is formed. When the wind is still and the air is cold (below -5 degrees Celsius), crystalline frost or rime can form as a result of the sublimation of water vapor and freezing of very fine droplets (usually associated with fog and haze). This type of frost, which forms throughout the year in the form of thin petal-like crystals (referred to as "frost flowers"), is not considered to be hazardous. Frost flowers are easily broken off and blown away from the wires of glaze measurement apparatus. The mass of this type of frost is small (20-28 grams per meter of wire [4, 45]). The mass of glaze and frost accretion increases with increasing height. Their diameter on the instrument wires typically increases by a factor of two between 2 and 10 meters elevation. The duration of glaze and hoarfrost/rime formation is usually 3 to 12 hours at a time, but it can be as much as 24 hours in some cases.
In the Arctic, glaze deposition about 5 millimeters in diameter is observed most commonly. Averaged over a 20-year period, the maximum number of cases with this type of ice deposition of 6 days per year is observed in the Kara Sea (Figure 45). To the east, the frequency of glaze decreases, and in the Laptev and East Siberian seas the number of days with glaze is 1 to 2. Only on Chetiryokhstolbovoy Island is the number of days greater than 5. In the eastern sector, the duration increases to 3 days in the Chukchi Sea.
Figure 49. Spatial distribution of the annually averaged number of cases with glaze 5 millimeters or more in diameter. Points denote locations where 1 to 2 cases with glaze 20 millimeters in diameter were recorded.
The spatial distribution of average glaze mass is shown in Figure 50. In the Arctic, glaze deposition to a diameter of 20 millimeters or more is observed very infrequently ñ at most 1 to 2 times in 20 years at most stations. Maximum average long-term frequency of 0.6 days per year was recorded in the northern Kara Sea.
Figure 50. Spatial distribution of the mass of glaze in g/m.
Heavy glaze was observed at 17 arctic stations. Dates and parameters of glaze at selected stations are presented in Table 51. On average, the glaze diameter was equal to 28 millimeters and the mass was 150 grams per meter. The maximum glaze diameter of 76 millimeters with a corresponding mass of 382 grams per meter was recorded on Uyedineniya Island. Maximum glaze mass of 960 grams (with a diameter of 43 millimeters) was observed at Cape Chelyuskin.
Table 51Cases of heavy glaze formation | |||
Station | Date | Diameter, millimeters | Mass, g/m |
Rudolph Island | 26 Aug 1984 | 20 | 128 |
Uyedineniya Island | 7 Oct 1967 | 20 | 147 |
24 Aug 1968 | 22 | 48 | |
25 Aug 1968 | 24 | 38 | |
7 Sep 1968 | 29 | 57 | |
4 Oct 1968 | 22 | 40 | |
10 Sep 1970 | 76 | 382 | |
12 Sep 1970 | 21 | 200 | |
20 Sep 1970 | 48 | 128 | |
14 Sep 1973 | 22 | 106 | |
28 Jul 1977 | 28 | 168 | |
3 Sep 1983 | 23 | 120 | |
Cape Zhelaniya | 2 Jun 1974 | 36 | 136 |
25 Jun 1979 | 26 | 144 | |
23 Sep 1980 | 25 | 320 | |
Golomyanny Island | 10 Sep 1970 | 52 | 40 |
26 Sep 1972 | 34 | 40 | |
7 Aug 1976 | 20 | 120 | |
Cape Chelyuskin | 21 Sep 1967 | 20 | 187 |
1 Oct 1969 | 23 | 188 | |
8 Jun 1972 | 26 | 264 | |
24 Jul 1980 | 43 | 960 | |
Preobrazheniya Island | 11 Sep 1979 | 25 | 144 |
6 Aug 1985 | 24 | 192 | |
Cape Shalaurov | 11 Jun 1970 | 20 | 98 |
Ayon Island | 7 May 1975 | 34 | 52 |
30 Sep 1975 | 23 | 130 | |
Cape Schmidt | 15 May 1970 | 20 | 80 |
Cape Netten | 19 Oct 1972 | 24 | 200 |
Heavy glaze is often recorded when wind speed is in the range from 2 to 10 meters per second (Table 52). After the growth stops, the glaze may remain on the wires for a long time. A case is known when individual pieces of glaze of 20 millimeters diameter persisted on the wires of a radio station over the entire polar winter into March.
Table 52Frequency distribution of wind speed with 20 millimeters or more of glaze, % | |||||
Station | Wind speed, m/s | ||||
0-1 | 2-5 | 6-8 | 9-11 | 12 or more | |
Amderma | 8 | 22 | 48 | 15 | 5 |
Uyedineniya Island | 7 | 35 | 46 | 11 | 1 |
Long-term variability in the number of days with glaze in the western Arctic area is presented in Figure 51.
The glaze formation process is very complicated. It is difficult to find a direct relation between the values of the meteorological parameters and glaze mass. The principal parameter is the amount of moisture in the air, and the intensity of ice accumulation depends on it directly. This moisture amount is estimated from the moisture content of the air flowing past and by the speed and direction of the wind with respect to the object's surface.
Figure 51. Long-term variability in the number of days with glaze (1) and frost (2) at the Marresalya station.
Glaze loading must be taken into account for designing electric power lines, construction of antennas and masts, and oil and gas platforms. The standard glaze load P (kilograms per meter) for ropes, wires, and cables is calculated using the formula:
P = p b (d + b) g 103,
where b is the thickness of glaze layer in millimeters, d is wire or cable diameter, g is glaze density, which is usually equal to about 0.8 grams per centimeter3 [64].
Cases of hoarfrost formation, including different sizes of crystalline or granular frost, occur quite frequently (up to 120 days per year) and are observed all year round.
Complex accretion events (snow with glaze and frost or rime) are seldom observed in the Arctic due to the frequent high winds which blow away the deposited ice. Usually, the granular frost remains on wires but rarely with wet snow. Data on dangerous accretion (more than 35 millimeters buildup) are presented in Table 53. On average, the diameter of dangerous accretion was equal to 48 millimeters and the mass was 93 grams per meter. This accretion was recorded when wind speed was very low - from 0 to 5 meters per second. The damage due to complex accretion was not significant, involving the breakage of various masts. Long-term variation in the number of days with frost in the western sector of the Russian Arctic is presented in Figure 51. Wet snow accumulation on the wires of the glaze measuring device (35 millimeters and more) was not observed over the entire 20 year period.
Table 53Data on complex accretion events with diameters of 35 millimeters or more | ||||
Station | Date | Max. diameter, millimeters | Mass, g/m | Wind speed, m/s |
Izvestiya TSIK islands | 24 Jan 1971 | 55 | 192 | 4 |
27 Jan 1971 | 55 | 290 | 3 | |
Dixon Island | 20 Jan 1970 | 44 | 126 | 3 |
Sterligov Island |
16 Jan 1973 | 43 | 159 | 4 |
Golomyanny Island | 01 Sep 1967 | 59 | 26 | 4 |
02 Sep 1967 | 36 | 24 | 2 | |
23 Jan 1968 | 48 | 40 | 3 | |
17 Sep 1968 | 42 | 40 | 5 | |
30 Sep 1968 | 36 | 38 | 3 | |
10 Sep 1970 | 66 | 80 | 4 | |
26 Sep 1970 | 36 | 40 | 2 | |
Cape Chelyuskin | 13 Jan 1969 | 48 | 88 | 2 |
Khatanga | 03 Jan 1969 | 36 | 38 | 4 |
Preobrazheniya Island | 15 Jan 1972 | 38 | 38 | 3 |
Chetyrekhstolbovoy Island | 14 Sep 1979 | 55 | 128 | 4 |
Ayon Island | 28 Sep 1975 | 62 | 248 | 2 |
16 Mar 1978 | 48 | 152 | 3 | |
Wrangel Island | 01 Jan 1979 | 45 | 112 | 3 |
01 Mar 1979 | 38 | 24 | dead calm | |
Cape Schmidt | 21 Mar 1975 | 35 | 48 | 7 |
Cape Netten | 21 Mar 1978 | 37 | 106 | 7 |
26 Mar1983 | 74 | 88 | 5 | |
09 Sep 1983 | 84 | 128 | 2 | |
08 Mar 1984 | 48 | 48 | dead calm | |
Uelen | 28 Jan 1980 | 84 | 75 | dead calm |
Hail is rarely observed in the Arctic and does not reach the level specified as hazardous (particle diameters of 20 millimeters or more). The atmospheric conditions do not occur that are needed for the formation of Cu congelatus clouds, which produce heavy hail (Table 54). If this type of cloud does appear, the intensity is significantly less than that in midlatitudes. Smaller sized hail (less than 10 millimeters in diameter) can occur, usually from June through September, but it is not observed every year (Table 55). For the 20 year period considered here, the total number of hail events at most of the stations ranged from 1 to 3, and in the Central Arctic Basin not a single case was recorded (Figure 52).
Figure 52. Spatial contours of the number of cases of hail over the 20-year period from 1966 to 1985.
Table 54Frequency (%) of Cumulonimbus and Cumulus clouds | |||||
North latitude | Cloud Type | Winter | Spring | summer | Autumn |
60-75degrees | Cb | 6 | 8 | 14 | 11 |
Cu | 2 | 6 | 14 | 3 |
The duration of hail falling is small averaging 5 to 10 minutes. Hail with a diameter of 40 to 50 millimeters and a mass of 30 to 35 grams (in the measuring device) was observed in the Subarctic near Norilsk at Nadezhda meteorological station on 25 June 1953. Its duration was 6 minutes. By way of comparison, the maximum weight of hail in midlatitudes was 1900 grams recorded in Kazakhstan.
Table 55Recorded Cases of Hail (1966-1974) | ||
Station | Date | Number of cases per season |
Maliye Karmakuly | 26 Aug 1973 | 1 |
Marresalya | 25 Sep 1971 | 1 |
03 Sep 1973 | 1 | |
Sopochnaya Karga | 4 & 16 Sep 1973 | 2 |
25 Aug 1974 | 1 | |
Cape Chelyuskin | 17 Aug 1966 | 1 |
21 Jun 1968 | 1 | |
31 Jul 1972 | 1 | |
22 Aug 1966 | 1 | |
19 Jul 1973 | 1 | |
Muostakh Island | 01 Sep 1968 | 1 |
Cape Shalaurova | 25 Sep 1973 | 1 |
Chokurdakh | 8, 26, 27 Aug 1966 | 3 |
Ambarchik | 12 Jun 1968 | 1 |
26 Jun 1970 | 1 | |
02 Jul 1974 | 1 | |
Cherskiy | 12 Jun 1968 | 1 |
Rau-Chua | 25 Jul 1972 | 1 |
01 Jul 1973 | 1 | |
26 Jun, 04 Jul 1974 | 2 | |
Kolyuchin Island | 30 Jun 1968 | 1 |
Cape Vankarem | 01 Sep 1973 | 1 |
Wrangel Island | 09 Jul 1973 | 1 |
Thunderstorms are considered to be HMPs. They impact negatively on economic activity in various ways. Lightning strikes may cause fires to break out at oil and gas processing facilities. Excess voltage on power lines can cause accidents. Interference with radio communication and radio navigation can occur.
The most dangerous events for aircraft are both direct lightning strikes and powerful vertical air flow inside the thunder clouds. Thunderstorms are observed when the cloudiness is strongly driven by convection and Cumulonimbus clouds are present. The frequency of such clouds in the Arctic does is less than about 5 percent in summer and 2 percent in winter [54]. These cloud types are observed more often in Subarctic regions.
Table 56Average and maximum number of days with thunderstorms (1936-1989) | ||||||
Station | Month | Seasonal Total | ||||
Jun | Jul | Aug | Sep | Average | Maximum | |
Rudolph Island | 0.05 | 0.05 | 2 | |||
Cape Zhelaniya | 0.04 | 0.3 | 0.2 | 0.5 | 3 | |
Maliye Karmakuly | 0.2 | 0.5 | 0.5 | 0.03 | 1.2 | 4 |
Amderma | 0.3 | 0.7 | 0.7 | 0.1 | 1.8 | 7 |
Ust-Kara | 0.3 | 0.8 | 0.5 | 0.04 | 1.7 | 9 |
Noviy Port | 1 | 2 | 1 | 0.1 | 4.1 | 12 |
Vize Island | 0.06 | 0.1 | 0.1 | 0.3 | 3 | |
Uyedineniya Island | 0.1 | 0.3 | 0.1 | 0.5 | 3 | |
Golomyanny Island | 0.02 | 0.2 | 0.5 | 0.02 | 0.7 | 2 |
Dixon Island | 0.1 | 0.1 | 0.3 | 0.5 | 5 | |
Russky Island | 0.04 | 0.3 | 0.1 | 0.4 | 2 | |
Cape Chelyuskin | 0.04 | 0.2 | 0.1 | 0.3 | 2 | |
Lake Taimyr | 0.08 | 0.9 | 0.6 | 1.6 | 7 | |
Preobrazheniya Island | 0.1 | 0.6 | 0.1 | 0.8 | 4 | |
Khatanga | 0.3 | 1.7 | 0.3 | 0.02 | 2.3 | 7 |
Kusyur | 0.8 | 1.9 | 0.9 | 0.02 | 2.6 | 8 |
Muostakh Island | 0.6 | 0.9 | 0.6 | 0.02 | 2.1 | 4 |
Kotelíny Island | 0.02 | 0.7 | 0.1 | 0.8 | 2 | |
Cape Shalaurov | 0.04 | 0.3 | 0.2 | 0.5 | 3 | |
Chokurdakh | 0.4 | 0.6 | 0.4 | 1.4 | 8 | |
Chetyryokhstolbovoy Is. | 0.2 | 0.4 | 0.2 | 0.1 | 0.9 | 3 |
Ayon Island | 0.2 | 0.3 | 0.1 | 0.6 | 2 | |
Cape Schmidt | 0.1 | 0.3 | 0.02 | 0.4 | 3 | |
Wrangel Island | 0.1 | 0.02 | 0.1 | 2 | ||
Uelen | 0.04 | 0.1 | 0.1 | 2 | ||
Average value for the Arctic | 0.2 | 0.5 | 0.3 | 0.02 | 1.0 | 4 |
Thunderstorms are rare in the Arctic. They are observed, as a rule, during the warm part of the year from June through September on average 1 day during the season (Table 56). They are not observed every year. The spatial distribution of the number of days with thunderstorms varies with latitude. The average long-term value decreases from south to north and is equal to 2 days per season on the coast of the Barents Sea, 1 to 1.5 days on the coast of the Kara and Laptev Seas, 0.5 days on the coast of the East Siberian and Chukchi Seas, and 0.1 days on the arctic islands (Figire 53). The maximum number of days per season (4.1) was recorded in Noviy Port on the Yamal Peninsula, and the minimum (0.05 days) was observed on Rudolph Island. Thunderstorms have not been observed in the arctic basin.
Figure 53. Spatial distribution of annual averages of the number of cases with thunderstorms (1966-1985).
The duration of thunderstorms per season averaged over all stations is 1.1 hours. The mean value per station varies from 0.02 hours on Rudolph Island to 2.3 hours at Lake Taimyr. The maximum duration of 6.3 hours per season was recorded at the southernmost station, Yuzhniy Port (Table 57). On average, the duration of thunderstorms is 0.2 hours in June, 1.1 in July, 0.4 in August, 0.03 hours in September.
Table 57Duration of thunderstorms in hours | ||||||||
Station | Month | Sum per season | ||||||
May | Jun | Jul | Aug | Sep | Average | Maximum | ||
Amderma | 0.2 | 1.1 | 0.9 | 0.1 | 2.3 | 5.6 | ||
Noviy Port | 0.1 | 1.0 | 3.7 | 1.4 | 0.1 | 6.3 | 8.5 | |
Uyedineniya Island | 0.02 | 0.3 | 0.2 | 0.5 | 5.5 | |||
Dixon Island | 0.1 | 1.0 | 0.2 | 1.3 | 8.8 | |||
Khatanga | 0.4 | 2.3 | 0.3 | 0.01 | 3.0 | 11.4 | ||
Cape Shalaurov | 0.05 | 0.5 | 0.2 | 0.7 | 6.1 | |||
Chetyryokhstolbovoy Is. | 0.2 | 0.7 | 0.3 | 0.1 | 1.3 | 4.8 | ||
Ayon Island | 0.1 | 0.2 | 0.05 | 0.2 | 3.7 | |||
Cape Schmidt | 0.1 | 0.3 | 0.02 | 0.4 | 5.2 |
8.3. Reflection of solar radiation and whiteout conditions
Among the specific hazardous phenomena in the Arctic we highlight the following phenomena. A clean snow cover in the spring can reflect more than 90 percent of the incident solar radiation when the sky is clear. Under these conditions, the use of dark glasses is a necessity. Extended exposure to this level of radiation causes pain in the eyes and can result in temporary blindness. Recovery requires that the person remain in a darkened environment for 2-3 days.
In spring in particular certain conditions can result in the danger of getting lost. This occurs when there is a complete stratus cloud cover and the sky becomes white and featureless. The horizon can become indiscernible as the sky blends with the snow cover, and there can be a loss of orientation. This event is called a "whiteout", which can produce uncertainty in a person's sense of direction and a loss of spatial orientation.