Chapter 8 Thunder, Lightening and Hail Lee Sang-Min 8 November, 2007

8.1 Patterns of vertical instability Thunderstorm - Period : June, 2000 ~ May, 2003 (4years) - Mean occurrence days : 30~45days - Distribution · Western > Eastern region · Approximately, 50% of them occurred in a mountainous & inland region due to the atmospheric instability caused by insolation in clear sky. · Usually occurred at 1~5 p.m.

8.1 Patterns of vertical instability Lightening - Period : 2005 (1year) - Seasonal Distribution (Lightening is dominant on summer.) · Spring : GyeongGi province · Summer : West & South sea (Western region in land) · Autumn : West sea, Chungnam & Jennam province · Winter : occurred rarely, but occasionally in coast region of Youngnam & Jennam province

8.1 Patterns of vertical instability Synoptic patterns caused by lightening mainly - Region at a pre-frontal Instability · squall line area - Region came to cold air (trough in 500hPa) come to the south at upper level · along the area expanding a cold air · mainly autumn - Region generated southwestern low-level jet prior to trough at 700hPa · lined with the low-level jet · mainly spring - Region generated southwestern low-level jet in a edge of Northwestern Pacific High & air-mass thunderstorm · lined with the low-level jet · mainly summer

Global Lightening Frequency World map showing frequency of lightning strikes, in flashes per km² per year. Lightning strikes most frequently in the Democratic Republic of the Congo.Democratic Republic of the Congo

8.1 Patterns of vertical instability Patterns of capping inversion - Dominant Case of high probability of thunderstorm occurrence with a strong convection - LCL ranked at low level due to a plentiful water vapor & a high temperature of boundary layer - Due to a strong inversed layer, Easy to accumulate a water vapor at low level & restrain a vertical motion - A trigger of vertical motion is available to generate a strong thunderstorm with emitting the latent heat at a stroke - 1 st instability pattern by Miller (Blustein, 1993)

8.1 Patterns of vertical instability Patterns of capping inversion - 3 p.m. 30th July, 1999 in Osan · formed a inversed layer at 700hPa · Continuous inflow of a water vapor from the west sea at low level · heavy rainfall on the record with 30 ~ 50mm per hour at nighttime 31th July (heavy rainfall on the record with 362mm in northern part of GyeongGi province in a day)

8.1 Patterns of vertical instability Patterns of capping inversion - Cause of a trigger to generate convective motion (According to Fig ) · Forcing of something at upper level · Inflow a water vapor at lower level · Warming at surface · Approaching a trough at upper level · Gust front of Mesoscale Convective Systems (MCS) · Convergence line of sea-land wind · Differential heating due to cloud at surface

8.1 Patterns of vertical instability 16th June, :50 a.m. Mesoscale Convective Systems (MCS) - Case of Secondary thunderstorm derived with MCS · Low pressure over Manchuria with -23 ℃ at 500hPa · Strongly developed MCS over North Korea · Development of thundercloud cell due to gust front derived with them · Shower with lightening in northern region of GyeongGi & some region of GangWon province · Obvious rope cloud due to cold air derived with MCS · Suddenly developed thunderstorm · released inversed layer & inflow a water vapor at direction of southwestern wind 07:30 a.m. 11:30 a.m. 09:00 a.m.

8.2 Hail Definition - A form of precipitation which consists of balls or irregular lumps of ice (hailstones) generated with repeated process of ascending and descending at freezing level in cumulonimbus. - Existence of strong vertical wind shear Condition of occurrence 1) Great vertical extent in cumulonimbus 2) Existence of strong vertical wind shear 3) More moist at lower level or short fall height (mountainous region) - Spring : inflow of warm air at lower level - Autumn : moving south of cold air at upper level - Usually in mountainous region of GangWon province in summer (MAY ~ SEP) : strong vertical wind shear

8.2 Hail Distribution of occurrence in Korea - Seasonal : Spring (APR) and Autumn (NOV) - Spatial · FEB~MAY : Western coast & inland region · MAY~AUG : GangWon mountainous & some inland region · OCT~DEC : West-middle sea & GyeongGi province region Damage of hail - Hail more than a diameter of 1.5cm (generated well in July due to abundant moisture) - Usually a mountainous region during summer - Before or after 5 p.m. when instability is extreme as air temperature rise cf. GangWon mountainous region : at noon due to mountain and valley winds & topographic effect (1989~1998(10years))

8.2 Hail Thermodynamic diagram Satellite image of GMS - Air-mass thunderstorm with high insolation in interior of high pressure · LFC at 700hPa · HapCheon & SanChung : hail with a diameter of 3~5cm due to topographical effect at noon - Instability pattern to be accompanied with cold front in spring · Real-latent instability to 500hPa · HapCheon & SanChung : hail with a diameter of 1~3cm 2th June, th May, 2000

8.2 Hail - Hodograph about Fig · Horizontal shear, CAPE · KwangJu : 12m/s, 479J/Kg · pohang : 28m/s, 41J/kg

악천후 속을 비행하다 우박을 맞아 비행기 앞 레이더돔이 떨어져 나가고 조종석 창문이 깨진 아시아나항공 8942 편