Weather Imagery

In February 1971, Dr. T. Theodore Fujita published a research paper entitled “Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity”. In the paper, he discussed how tornadoes should be rated on a scale to better understand the damage associated with intensity and wind speed. Over the next few years and the super outbreak of 1974, Dr. Fujita’s scale for measuring tornadoes became invaluable and the F-Scale became widely adopted.

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Hail forms in thunderstorms where the updraft is strong enough to carry water droplets and ice condensing nuclei high into the atmosphere where they interact and freeze turning into ice. When the weight of the ice is too heavy for the updraft to keep it suspended in the cloud or when the hail falls outside the updraft and is allowed to fall back to the ground, a hailstone is created.

Hail Formation

The dynamics behind what creates the hail is somewhat complex. The basic ingredients are ice condensing nuclei, super cooled water droplets, latent heat, and powerful updrafts. In order for ice to form, super cooled water must come in contact with an ice condensing particle such as dust, pollen, or insects. By supercooled, I mean the temperature of the droplet is less than 32°F yet remains in liquid form. If these ice condensing nuclei aren’t present, water droplets can become super cooled and remain unfrozen. An updraft from a thunderstorm however will carry with it dust, pollen, and insects which will collide with the super cooled water droplets. Once the water droplets touch an ice condensing particle, the super cooled water instantly freezes and turns to ice (same principal behind ice forming on an aircraft wings).

Hail Growth

At this point, the hail is very small and is easily moved by air currents. As the small hail makes contact with other super cooled water droplets, more ice forms around the hail until it grows large enough that it begins to fall from the sky due to its increased weight. The updraft of the thunderstorm is what keeps the hail suspended in the air. The longer the hail remains in the air, the larger the hailstones become. Once the hail grows too large and gains weight, the wind can no longer keep it aloft. It then falls the the ground as hail.

Hail Size

Although small hail can form anytime there is super cooled water, ice condensing nuclei and an updraft, large hail can only form when the updraft is powerful and tilted or spiraling. As the hail gets carried high into the thunderstorm it gets shot out the top like a popcorn machine. If the updraft is vertical in nature, the hail will fall outside the updraft and eventually hit the ground. However, if the updraft is tilted, some of the hail will re-enter the updraft as it’s falling and go through the growth cycle all over again. If the updraft is powerful enough, it can lift some pretty heavy hailstones and keep them suspended for hours until they become so large that the updraft is no longer capable of lifting them high into the cloud anymore.

Pea (0.25 in.) Half-inch (0.50 in.) Dime (0.75 in.) Nickel (0.88 in.) Quarter (1.00 in.) Half Dollar (1.25 in.) Ping Pong Ball (1.50 in.) Golf Ball (1.75 in.) Hen Egg (2.00 in.) Tennis Ball (2.50 in.) Baseball (2.75 in.) Tea Cup (3.00 in.) Grapefruit (4.00 in.) Softball (4.50 in.)

The largest hailstone ever to fall in the United States (as seen above) had a 7 inch diameter, 18.75 inch circumference and fell in Aurora, Nebraska on June 22nd, 2003. What’s even more remarkable is, NOAA officials think 40% of the stone broke off when it hit the gutter of the house and another percentage melted before they actually got to it. Yet after all that, it still broke the record!

Why Hail Looks the Way it Does

If you have ever been in a hailstorm, you most likely noticed there are different sized hailstones. Some large and some small. As mentioned above, some hail will re-enter the updraft (larger hailstones) while others will miss it (smaller hailstones). The larger hailstones look knobby or clumpy because as they re-enter the updraft, other hailstones will collide and freeze together. This gives them a very irregular and clumpy look. The smaller hailstones on the other hand, may look more smooth but may still be irregular in shape. These hailstones probably didn’t make too many round trips in the updraft because they didn’t get a chance to collide and clump together.

Hurricanes are the most powerful storms on Earth in terms of size, energy released, and the scale of damage thay can produced. If the winds are troublesome enough, the storm surge can be as high as 25 feet and often times causes more damage than the wind. However, tornadoes sometimes accompany the hurricane which makes some locations sustain far greater damage than the surrounding areas.

The terms typhoon and hurricane mean the same thing, that is, they are both non-frontal synoptic scale low-pressure systems over tropical or sub-tropical waters with organized convection (i.e.; thuderstorm activity). They name corresponds to their geographic location of where they formed. For example, typhoons form in the Northwest Pacific Ocean west of the dateline. Hurricanes form in the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E.

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I always find extreme weather records fascinating because some of them will just blow you away. If you think the weather is miserable or crazy where you live, take a look at some other places around the world. I think you’ll find most of these records absolutely mid boggling.

Temperatures

• Coldest temperature in USA: -80°F at Prospect Creek Camp in the Endicott Mountains of northern Alaska on Jan. 23, 1971
• Hottest temperature in USA: 134°F in Death Valley, CA on July 10, 1913
• Coldest Temperature in the World: -129°F in Vostok, Antarctica on July 21, 1983
• Hottest temperature in the World: 136°F in Al’ Aziziyah, Libya on September 13th, 1922
• The USA hottest average temp: 77.7°F in the Florida Keys, FL.
• World’s hottest average temperature: 94°F in Dakol, Ethiopia
• Worlds highest dew point temperature: 95°F in Dhahran, Saudi Arabia on July 8, 2003
• The largest 2-minute temperature change of +49°F occurred in Spearfish, South Dakota on January 22, 1943, at about 7:30am MST where the temperature rose from -4°F to 45°F.
• The largest 24-hour recorded temperature change occurred on January 15, 1972 in Loma, Montana, where the temperature rose from −54°F to 49°F.

Rain

• The 1-minute world record rainfall amount is 1.23 inches which occurred on July 4th, 1956 in Unionville, MD.
• The 12-hour world record rainfall amount is 45.0 inches was set at Foc-Foc on La Reunion Island.
• The 24-hour world record rainfall amount is 71.8 inches was set at Foc-Foc on La Reunion Island.
• The 48-hour world record rainfall amount is 97.1 inches was set at Aurere on La Reunion Islands.
• The 72-hour world record rainfall amount is 127.6 inches was set at Grand-Ilet on January 24th-27th, 1980.

Snow

• Mount Baker, Washington received a record 1,140″ of snow in one season (1998-1999).

Wind

• Scientists measured the fastest wind speed ever recorded, 318 mph, in one of the tornadoes that hit the suburbs of Oklahoma City on May 3, 1999. The 318 mph speed would put the tornado only 1 mph below an F-6 on the 0-to-6 Fujita scale. No tornado has ever been classified an F-6.
• Two weather stations with the lowest recorded annual wind speeds are Talkeetna, Alaska and Medford, Oregon, both with annual winds of 4.8 mph.
• St. Paul Island, Alaska is the city with the highest annual average speed of 17.6 mph. Mount Washington is higher at 35.3 mph, but only scientists who work at the weather station live there.

Tornadoes

• Longest Track: The Tri-state Tornado that hit Missouri, Illinois and Indiana on March 18, 1925 which traveled 219 miles.
• Highest Wind Speed: Oklahoma City on May 3, 1999 with a wind speed of 318 mph.
• Most Deadly: The Tri-state Tornado that hit Missouri, Illinois and Indiana on March 18, 1925 which killed 689 people.
• Widest: The Wilber/Hallam, Nebraska tornado during the outbreak of May 22, 2004, with a width of 2.5 miles.
• Costliest: The Oklahoma City tornado of May 3, 1999 caused $1.2 billion dollars in damage.

Hurricanes

• Hurricane Camille (August 17, 1969; 256 deaths) and the 1935 “Labor Day” hurricane are the only two Category 5 hurricanes to make US landfall.
• Lowest Barometric Pressure (Atlantic): Hurricane Wilma on October 19th, 2005 at 884 mb.
• Lowest Barometric Pressure (World): Typhoon Tip in the northwest Pacific Ocean on Oct. 12, 1979 at 870 mb.
• Most Rapid Intensification: Wilma went from Tropical Storm to Category 5 in 16 hours with a wind speed increase from 70 mph to 155 mph.
• Most Hurricanes in 1-year: 2005 with 15 named hurricanes.

Air Pressure

• The highest official sea-level pressure was 32.01 inches of mercury in Agata, Russia on Dec. 31, 1968
• The highest in North America was 31.85 inches of mercury at Northway, Alaska on Jan. 31, 1989.

Other Records

• The sunniest city in the United States is Yuma, Arizona, which receives 90% of possible sunshine.

At some point, most of us have heard that water spins down a drain in different directions depending on which hemisphere we happen to be in. The fact is, the Coriolis force (an apparent force as a result of the Earth’s spin) has virtually nothing to do with which direction water spins as it empties down a drain. Although this force is “real” and does have an affect on other large, long-lived systems that travel great distances (such as hurricanes, high and low pressure systems, and long range artillery shells), water draining from toilets, sinks, and bathtubs are rendered virtually immune from its affects. The Coriolis force is much too weak to have any affect on such small, short-lived rotating bodies of water under normal conditions.

rotation and has different magnitudes depending on how close or far you are away from the poles and the equator. As you move closer to the equator, the Coriolis force weakens. Keep in mind that at the equator the Coriolis force has no affect on any object. So what about water going down a drain? Is it affected or not? Let’s look at some other things first.

As a demonstration, imagine that a merry-go-round represents the entire surface area of either the northern or southern hemisphere of the Earth. If you start in the center of the merry-go-round and walk towards the edge as it’s spinning, you will start to feel a deflection and will find yourself drifting to one side or the other (depending on which way you spun the merry-go-round). Now, if something moved a comparably equal distance in one of the Earth’s hemispheres (such as a hurricane does), it too will be deflected. The merry-go-round is an exaggeration because nothing moves over a comparable distance on the Earth in the same amount of time. But you can sort of get the picture that the Earth is huge and a little toilet of water very small in comparison.

On the Earth, hurricanes and pressure systems move hundreds of miles over a period of days and they are most certainly affected by the Coriolis force. In a low pressure system, air flows towards the center and as it does so, it is deflected to the right in the northern hemisphere and to the left in the southern hemisphere. If the Earth were to stop rotating, there would be no deflection and the low pressure system would quickly equalize as the air rushed towards the center. However, on a rotating Earth the air keeps getting deflected away from the center which causes the low pressure system to spin counter-clockwise in the northern hemisphere (depicted below in the graphic) and clockwise in the southern hemisphere. In a high pressure system, air flows out from the center. In the northern hemisphere, the deflection is to the right which causes the system to spin clockwise. In the southern hemisphere, the deflection is to the left which is why a high pressure system spins counter-clockwise. The fact that the Coriolis force is “zero” at the equator is the reason why no hurricanes cross from one hemisphere to the other.

As for water emptying down a drain, the amount of deflection produced by the Coriolis force is a couple orders of magnitude too small compared to other influences. It’s not that the Coriolis force doesn’t exist, it is just too weak to have any influence on such a small amount of water in an 18″ toilet bowl or sink as compared to a hurricane which is hundreds of miles across and moves thousands of miles. The only things that affect which way the water empties down a drain is the shape of the container it’s draining from, the way the water was introduced into the container, irregular eddies, and any other objects which may affect currents in the bowl. So in the case of a toilet, take a look and observe which way the water jets into the bowl and see if your toilet bowl is perfectly round. Chances are the water enters at an angle and the bowl itself is elliptical. All you need is a small rotation at the start and as the water empties towards the bottom of the toilet/sink, the water will begin to rotate faster due to the narrowing of the drain (same principal as when an ice skater pulls their arms in towards their body … they spin faster). So the next time a scam artist in another country offers to demonstrate this “water down a drain phenomenon” by stepping on the other side of the equator where the Coriolis force has zero affect, save your money!

Some things affected by the Coriolis force are Long range artillery shells that “fly” 20 or more miles. The affect is much smaller than a hurricane, but still needs to be taken into consideration so the shells hit the right target. A 50-yard difference could have disastrous results. Ballistic missiles must really take the Coriolis force into consideration because they will travel thousands of miles at great speeds. Ocean currents span the entire globe and as a result they too are affected by the Coriolis force. Interestingly, a tornado is not affected by the Coriolis force. In fact, about 10% of tornadoes spin clockwise while about 90% spin counter-clockwise in the northern hemisphere. However, the meso-cyclones, supercells, and low pressure systems which are responsible for spawning tornadoes are affected by the Coriolis force, which in turn tend to bias tornado genesis.