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Home , Hurricane Isabel, Thermal low, Tropical cyclone naming

Week 10: lecture 8 class notes Section 1: Other atmospheric cooling and warming methods

• further processes for warming and cooling the atmosphere; • cool and warm core low pressure systems; • hurricanes in depth. • review for homework 2 (supplemental notes) • warming and cooling the atmosphere - other processes Another way of warming air: 1. when water vapor condenses, a certain amount of thermal energy is “given” to the atmosphere. -Condensation is a warming process 2. the amount of heating is proportional to the amount of water that condenses. At temperatures and pressures, the warming is about 590 calories for each gram of water that condenses. The 590 calories is known as “latent heat”. 3. since air with 100% relative humidity at lower dew point temperatures holds less water than air with 100% relative humidity at higher dew point temperatures, much more heat is liberated in cases for which cloud development is occurring in high dew point environments. • For example, air that has 100% relative humidity at 10° C has about 8 grams of water vapor per kilogram of air, while air that has 100% relative humidity at 30 degrees C has about 32 g/kg. If the kilogram air parcel initially at 10 degrees Celsius is lifted and cooled so that all the water vapor condenses out of the parcel, approximately 4720 calories would be liberated. Similarly, if the 30- degree parcel were also lifted, 18880 calories would be liberated… • This tremendous heating due to latent heat release makes the core of hurricanes and monsoonal thermal lows that have access to humid air much warmer, say, at 500mb level, than can be accounted for by the actual surface temperatures alone. • The same sort of heating also occurs when very humid air (with high surface dew points) is lofted in the warm sector of mid-latitude wave . This excess heating is so marked, that the air parcels become like hot air balloons that accelerate their upward progress if they are warmer than the surrounding air at the same elevation. This accounts for the blossoming of cumulonimbus clouds (and, therefore, thunderstorms) in areas with high dew points. Another way of cooling air: 1. Conduction Cooling- (Advective) a. Air flows over a cold surface and is cooled by conduction (this process is termed advective cooling). If the cooling is enough to take the air parcel’s temperature to the dew point, the resulting condensation will produce a layered cloud on the ground. • California’s coastal advection fog b. Are “sits” on a surface that gets cold overnight. (this process is termed radiation cooling). If the cooling is enough to take the air parcels temperature to the dew point, the resulting condensation will produce a layered cloud on the ground. • California Central Valley tool or radiation fog. 2. Expansion Cooling- (Radiation) a. Air expands, molecules get “farther apart”, do not strike each other as often, do not “vibrate” as much. Air expands when pressure around moving air parcels decreases markedly. Best example -- air involved in vertical motion. • Rising are experiences cooling at dry adiabatic rate of 5.5 degrees Fahrenheit/1050 ft. This is one of the ways in which the air is cooled to the dew point.

Warm and cold low pressure -Review Two types of vertical motion: Buoyant (thermal) (warm core) • air rises because it is less dense than its surroundings Forced (Dynamic) (cold core) • up over a hill • warmer air over colder air • horizontal convergence Cold core low pressure

• Rising air in all levels of the atmosphere • cover a relatively small synoptic scale area compared to high pressure systems. Their path can heavily totals. • Developed cold core lows tilt to the Northwest with height • Coldest temperatures are at Center of low. • Air is cooled by adiabatic expansion and evaporational cooling of and/or snow. • Most mid-latitude Cyclones are cold core lows • They caused widespread precipitation. • They are deep cored. Developed cold core lows will show at each mandatory level. They will have closed height contours in the low levels and shows as a synoptic scale trough in the upper levels. Warm core low pressure 1. Type 1: Thermal Low • Thermal lows are shallow and most intense at surface. • Develop due to strong surface heating. • Hot air due to intense thermal build-up results in positive buoyancy at the surface. • Mid and upper levels are stable. • Most common in Southwest US during the summer. • Develops over land (especially dry land with little vegetation)

2. Type 2: Tropical Low • Deeper than thermal low, although they do not weaken with height in upper levels. • Subsidence (sinking) air in center causes compressional warming. • Air rises rapidly around edges of (eye wall) • Develops over water • Warming core low is strongest when virtually stacked. Significant shear will weaken warm core low. This is the opposite situation of a cold core low; Strong core lows tilt with height.

a. Cold Core Low Pressure b. Cold Core High Pressure c. Warm Core Low Pressure d. Warm Core High Pressure Why syncing air in the center: -Centrifugal force operates outwards and cancels the effect of friction once speeds reach 74 miles per hour, so air cannot cross the isobars right near the center. -A partial vacuum is caused, so air must be replaced and sinks from above, causing clear, calm conditions.

-Why sinking air occurs in the center (eye) of a warm core low (hurricane). Tropical è air flows into center of low to replace air diverging off the top • (Week 8, slide 13) Tropical Cyclones aka Hurricanes Huracan è named after Caribbean God

• Combines energy of wind and water • Severe defined by high velocity that rotate around a central low-pressure core. • Cyclones • • Form over tropical between 5° - 20° degrees of latitude • Rotation of the earth affects their spin -Caused by…

• weather disturbances • Thunderstorm that pulls in surface are from all directions -At 80° Fahrenheit or warmer -In about 200 feet of water. Over several hours to days, the storm intensifies. Reaching hurricane status when the winds are rent around it reaches a sustained speed of 74 miles per hour or more.

Eyeè 5-120 mi. across Eyewallèmost powerful winds and heaviest rainfall Rain Bandsè 52-300 mi. wide

• Storm is pushed into motion by • Eventually turns away from the tropics and into mid-latitudes • Weakens and breaks apart once they move over cold water or land • Lifespan can be as short as a day or as long as a couple of weeks • They become natural disasters on land • They release 200 times the energy released by all the world’s power plant combined, on average in a single day -Hurricane-force winds can extend over an area 150 miles wide - force winds can extend 300 to 400 mile wide stretches -Water causes the most damage

• 15 to 20 feet high, 50 to 100 mile wide Dome of waterè -Can devastate a low-lying coastal areas. -Torrential can lead to flash and long-term flooding What is a tropical ? -Cyclonic system over tropical waters

• between 5° - 25° degrees N/S latitude • but not at the equator because of the Coriolis Force (CF)=0 • CCW in the Northern hemisphere Classification: Tropical disturbance

• no circulation Tropical depression

• max sustained windsè less than 38 mph Tropical storm

• 39 to 73 mph (aka Hurricane)

• 74 mph and over Tropical Cyclone naming Hurricane -Carib God ‘Huracan’, Mayan God ‘Hurakan’

• North Atlantic, Northeast Pacific

• the Northwest Pacific Ocean Severe Tropical Cyclone

• the Southwest Pacific or Southeast Severe Cyclonic Storm

• North Indian Ocean Tropical Cyclone

• southwest Indian Ocean Hurricane Season

• June 1st through November 30th Eastern Pacific

• May 15th through November Western Pacific

• year-round Indian Ocean

• April through December Tropical vs Mid-Latitude Storms

• Warm water versus differences and air masses • Warm vs. Cold Core • Fronts vs no fronts • 1/3 size Tropical Cyclone Ingredients -warm tropical waters (5°-25° degrees N/S latitude)

• Equal to/ greater than 82° Fahrenheit or 28° C • Gigantic heat engine • Release of latent heat -weak upper winds • little • more wind shear during typical El Nino Typical Atlantic Cyclone regions

• from to the Caribbean Tropical Cyclone Formation

• Begin as Tropical Disturbances (Easterly Wave) • 90% die out before becoming depression • Small clusters of thunderstorms • is a favored region Hurricane structure

• Week 8, slides 26-28 Hurricane Eye -Average 15 mile diameter -Range 3.5 to 60 miles -Eye wall

• Outer Perimeter of eye • Most intense storm activity • strongest winds, thickest cloud cover, most intense precipitation -Inside Eye

• blue skies, calm winds, no precipitation, fair weather cumulus -shrinking eyeèintensifying hurricane Hurricane Eye

• the “stadium” -diagramè week 8, slide 31

Hurricane Miscellany -length of time

• averageè eight days • longestè 31 days, Hurricane/Typhoon John (1994) -average forward speed

• 14 miles per hour -diameter

• 50-500 miles • Averageè 100-120 miles -most intense

• Typhoon Tipè 190 miles per hour (870 MB) (1400 mile diameter) Hurricane Climatology Atlantic Basin -Average: • Tropical Storms-10 • Hurricane- 6 • Major Hurricanes- 2

-Most: 2005 • Tropical Storms- 27 (Beta, Gamma, Delta, Epsilon, Zeta) • Hurricanes- 13 • Major Hurricane- 7 U.S. Hurricane Climatology Deadliest:

• 8000 to 12000 deaths- Galveston (1900) • 1,836 deaths- Lake Okeechobee (1928) • 1,336 deaths Costliest:

• $75 billion- Hurricane Katrina (2005) • $60 billion- (2012) • $45 billion- (1992) • $13 billion- (2011) Tropical Cyclone Tracks

• week 8, slide 35-37 Typical Cyclone Regions

• Atlantic basin (only north of the equator?) -Week 8, slides 39-44 (by the month) Hurricane Season -Week 8, slide 45

• Peaks in September U.S. Landfalling Hurricanes -week 8, slide 46 (map of all us hurricanes)

• only three Category 5s 2019 Atlantic Storms and Hurricanes Named stormsè 9-15 Hurricanesè 4-8 Major Hurricanesè 2-4 2019 Landfalling Hurricanes -week 8, slide 48 Hurricane Naming

• Saints names in Latin America • World War II military names • 1950-1952 phonetic alphabet • 1953-1978 women’s names • 1978-present -Mixed names by WMO -male/female -Anglo, Latin, French • Retired names for infamous storms Names (2019-2024) -week 8, slide 50 Retired Hurricane Names

• particularly deadly or infamous (list) -week 8, slide 57 • Total: -77 storms have been retired since 1954 California Tropical Storms?

• Only one hurricane -October 2nd, 1858 -San Diego • Only one tropical storm -September 25th, 1939 -Long Beach -45 fatalities, mostly fishermen -one of four 1939 storms impacting California • Water temperature too cold (i.e. èis less than 82 degrees Fahrenheit) Saffir-Simpson Scale Category 1: 74 to 95 miles per hour >980 MB

• flooded coastal roads • minor pier damage surge • 4 to 5 feet Category 2: 96 to 110 miles per hour 965-979 MB

• flooding 24 hours before eye • piers damaged • surge 6-8 feet Category 3 (major): 111 to 130 miles per hour 945-964 MB

• small buildings destroyed • flooding 3-5 hours prior • surge 9-12 ft Category 4 (major): 131 to 155 mile per hour 920-944 MB

• major flooding, major damage • surge 13-18 ft Category 5 (major): 155 miles per hour 920 MB

• flooding, extreme damage • surge>18 ft Saffir-Simpson Frequency Category 1è65 Category 2è43 Category 3è55 Category 4è15 Category 5è3 Tropical Cyclone Hazards

• Storm surge -ocean can rise up to 25 feet • High winds -gusts up to 200 miles per hour • Flooding from rainfall -up to 40 inches of rain • Tornadoes -spawned by the hurricane up to 1,000 miles inland Storm Surge

• surface wind converges • surface water diverges • huge “dome” of water pushed ahead of storm Before/After Storm Surge -week 8, slides 57-62 Hurricanes are Right-Handed

• storm surge and winds are higher on the right side -right front quadrant (RFQ) -week 8, slide 63 -week 8, slide 65-66 Tornadoes

• clusters of tornadoes • most often right front quadrant • occur away from Center • landfall spawns tornadoes Hurricane Fatalities

• freshwater floodingè 59% • windè 12% • surfè 11% • offshoreè 11% • tornadoè 4% • otherè 2% • surgeè 1% U.S. Hurricane Deaths and Damage The US has fewer hurricane deaths the…

• 1920 to 1929è 2,130 • 1930 to 1939è 1,050 • 1940 to 1949è 220 • 1950 to 1959è 750 • 1960 to 1969è 570 • 1970 to 1979è 226 • 1980 to 1989è 161 • 1990 to 1996è 147 The cost of hurricane damage has increased… (1996 dollars in billions)

• 1920 to 1929è $1.9 billion • 1930 to 1939è $5.1 billion • 1940 to 1949è $4.9 billion • 1950 to 1959è $13.3 billion • 1960 to 1969è $20.9 billion • 1970 to 1979è $21.5 billion • 1980 to 1989è $19 billion • 1990 to 1996è $40.9 billion Top 10 Costliest Storms (1900 to 2010) -week 8, slide 70 Galveston, Texas

• 1900, Galveston Island, Texas • 9 foot storm surge • single deadliest natural disaster in US history -over 6,000 people drown in rising seas -few took the warning seriously -even visitors went to see the waves Bangladesh (East Pakistan)

• Tropical Cyclone Sidr -Bay of Bengal • 1970- 500,000 killed by Cyclone Bhola • 1991- 130,000 killed • near sea level • poor construction • most people killed by flooding Hurricane Andrew (1992) -week 8, slide 74 (1998) -week 8, slide 75-76 (2003) -week 8, slide 77-81 Hurricane Katrina (2005) -week 8, slide 82-86 Tropical (May 2008) -week 8, slide 87 Hurricane Forecasting

• Tropical Prediction Center, Coral Gables, • “Hurricane Hunters” fly into the storms -radar and dropsondes • computer models (NWP) -statistical uses information from past hurricanes -dynamic current information plus laws of physics -hybrid combination of both Hurricane Watches & Warnings

• watch -landfall predicted in more than 24 hours • warning -landfall predicted in less than 24 hours • unpredictability makes decision difficult -evacuation -people killed -costs -week 8, slides 90-92 Hurricane Sandy -week 8, slides 93-96 -week 8, slide 97-104

Reading Assignment • THU, APR 9th, 16th and 23rd 1. Pielke and Pielke; Chapters 3 and 5. (Hurricanes and Hurricane Impacts) 2. Simmons and Sutter: Chapter 6 -- Sections 6.4, 6.5, and 6.6 ( Casualties, Damage, and Association with Disaster) 3. Williams :Chapters 4, 8, and 9; Hurricanes (Fronts, Thunderstorms, Tornadoes, Forecasting) 4. Zebrowski: Chapters 5 pp. 131-135 (completes our reading of Chapter 5); Chapter 8 251- 262 (completes Chapter 8) (Waves, Tsunami and storm surges), Hurricanes, Thunderstorms, Tornadoes)