I recently was given the opportunity to conduct undergraduate research with a group of students from the University of Michigan, Virginia Tech, and University at Albany. We were headed to Greenland to conduct experiments on the atmospheric and geological conditions there.
This all started back in 1926 when professor William Hobb’s took the first atmospheric and geological experiments. He was a professor at University of Michigan, and since then there have been three other trips (including the one I was on) recreating the first one organized by William Hobb.. The most recent one was in 2006.
The 14 students from various universities geared up and all met in Albany NY. From there we did some classroom learning to get to know all the instruments we were going to be using. (If time allotted, you should definitely list out some of the instruments that you learned about!) It was really interesting working with students who had different majors and different skill sets. This allowed for many ways to solve a problem or a creative way in completing a task at hand.
Shortly after our Albany meet up, we loaded up in a C-130 and headed to Greenland. We were lucky to get to go at this time of year as they are in their summer. This means that there is 24 hours of sunlight. We had all the time in the world to go on hikes and conduct research because the sun never set!
We were all given these instruments and we told that this was our experiment, and we needed to figure out what we wanted to measure. A completely normal task that students have to figure out when conducting their own research, but we were undergraduates, and we had never done our own research. It was like letting a kid go loose in a candy shop – there were so many different things we could do!
We finally decided to do four different experiments.
The moral of this story, and the most important part, is that undergraduate research is so hard to come by. It opens doors for students and helps them discover more and more things about not only the weather but the climate, especially in regions that aren’t as explored – like Greenland. Being able to conduct this research at such a young age, made a lot of people on the team interested in going to graduate schoolor looking into research they can do on their own.
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@2019 Weather Forecaster Allison Finch
Many of us are aware of what a tropical cyclone (hurricane) is, but what about an extratropical one? Extratropical cyclones (aka mid-latitude cyclones) are those that we witness all year round here in the continental U.S. They are simply low pressure systems. Low pressure systems, unlike high pressure systems, rotate counterclockwise. This helps to create convergence since the air is converging towards the center and will want to rise. Thus, clouds and precipitation usually form, if other conditions are also right. These extratropical systems are frequently the cause of our precipitation, especially the stronger and heavier storms. This is because of the greater instability that is present, meaning the atmosphere has a lot of energy to work with. Typically, the stronger the system, the stronger the storm . For instance, many tornadic storms are the result of strong extratropical systems.
An extratropical cyclonegets its energy from the horizontal temperature contrasts that exist in the atmosphere. The temperature contrasts help to provide the forcing and instability needed for storm development in the form of frontal systems. These include cold fronts, warm fronts, and occluded fronts.On the other hand, tropical cyclonesare barotropic in nature, meaning there is constant pressure and density. This type of atmosphere results in no fronts and little temperature differences across the storm at the surface. Tropical cyclone winds are derived from the release of energy in the form of latent heat. Latent heat is energy which is transferred from one substance to another, such as evaporation and condensation processes. In the case of a tropical cyclone, it is due to cloud/rain formation from the warm moist air of the tropics. Furthermore, Tropical cyclones have their strongest winds near the surface of the Earth. In contrast, extratropical cyclones have their strongest winds near the tropopause, which is about 8 miles above the surface. These differences are due to the tropical cyclone being "warm-core" in the troposphere, whereas extra-tropical cyclones are "warm-core" in the stratosphere and "cold-core" in the troposphere. A “warm-core” system refers to a system which is warmer than its surroundings. A schematic view which shows the difference between “warm-core” cyclones (tropical) and “cold-core” cyclones (extratropical) are shown below.
As far as the similarities between the two, tropical cyclones and extratropical cyclones are both symmetrical. They also have surface areas of low pressure with winds that rotate counter clockwise. Furthermore, both produce very heavy precipitation and often times results in flooding. Both tropical cyclones and mid-latitude cyclones can last for several days, and sometimes as long as a week or more.
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@2019 Meteorologist Corey Clay
New research has found the record-breaking South American drought of 2013/14 with its succession of heatwaves and long-lasting marine heatwave had its origins in a climate event half a world away - over the Indian Ocean.
The findings published in Nature Geoscience by an international research team with authors from the Federal University of Santa Catarina in Brazil, Australia's ARC Centre of Excellence for Climate Extremes and NOAA in the U.S. suggest this may not have been the first time the Indian Ocean has brought extraordinary heat to the region.
It all started with strong atmospheric convection over the Indian Ocean that generated a powerful planetary wave that travelled across the South Pacific to the South Atlantic where it displaced the normal atmospheric circulation over South America. These atmospheric waves are similar to ocean swells generated by strong winds that travel thousands of kilometers from where they were generated. Large-scale atmospheric planetary waves form when the atmosphere is unstable, and this disturbance generates waves that travel around the planet.
"The atmospheric wave produced a large area of high pressure, known as a blocking high, that stalled off the east coast of Brazil," said lead author Dr Regina Rodrigues. "The impacts of the drought that followed were immense and prolonged, leading to a tripling of dengue fever cases, water shortages in São Paulo, and reduced coffee production that led to global shortages and worldwide price increases." That impact wasn't just felt on land as the high-pressure system stalled over the ocean. "Highs are associated with good weather. This means clear skies -- so more solar energy going into the ocean -- and low winds -- so less ocean cooling from evaporation. The result of this blocking high was an unprecedented marine heatwave that amplified the unusual atmospheric conditions and likely had an impact on local fisheries in the region."
The researchers found this atmospheric wave was not an isolated event and that strong convection far away in the Indian Ocean had previously led to drought impacts in South America. "Using observations from 1982 to 2016, we noticed an increase not only in frequency but also in duration, intensity and area of these marine heatwave events. For instance, on average these events have become 18 days longer, 0.05°C warmer and 7% larger per decade." said CLEX co-author Dr. Andrea Taschetto. The 2013/14 South American drought and marine heatwave is the latest climate case study to show how distant events in one region can have major climate impacts on the other side of the world.
"Researchers found that Australia's 2011 Ningaloo Nino in the Indian Ocean, which completely decimated coastal ecosystems and impacted fisheries, was caused by a La Niña event in the tropical Pacific," said Australian co-author Dr. Alex Sen Gupta. "Here we have yet another example of how interconnected our world is. Ultimately, our goal is to understand and use these complex remote connections to provide some forewarning of high impact extreme events around the world."
Regina R. Rodrigues, Andréa S. Taschetto, Alex Sen Gupta, Gregory R. Foltz. Common cause for severe droughts in South America and marine heatwaves in the South Atlantic. Nature Geoscience, 2019; DOI: 10.1038/s41561-019-0393-8
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© 2019 Oceanographer Daneeja Mawren
What Are Pyrocumulus Clouds?
Pyrocumulonimbus cloud in Northern California in July 2014. Source: NASA Earth Observatory
From California to the Arctic, wildfires have been in the headlines for months now; their effects have been nothing short of far-reaching, as their smoky plumes have transported smoke to areas that are hundreds, if not thousands away from their sources. Such has been the case in Alaska, where significantly above-average temperatures have resulted in several uncontained wildfires. Their smoke plumes soon spread and et transported by atmospheric wind motions up into higher levels of the troposphere. In many instances, these conditions result in the development of a unique cloud type referred to as pyrocumulus clouds.
Wildfire in the Arctic Circle. Source: New York Post
These cloud types are essentially produced in much the same way that all other cloud types are; as the air around the wildfire heats up, its lighter density than the surrounding air allows for it to rise, bringing with it both the particles from the smoke and any water vapor that gets attached to said particles at the surface level. Once they condense, these particles and the water vapor that clung to them become what we refer to as a pyrocumulus cloud.
Pyrocumulus developing in Northern California. Sourvce: NASA Earth Observatory
As a wildfire continues to expand, so too does the area of greatest surface heating. As a result, those same vertical motions that helped to produce the initial pyrocumulus cloud will increase in intensity, resulting in more particles and water vapor making up and into higher levels of the troposphere. In some instances, these clouds can reach heights of up to 8 kilometers (5 miles), resulting in the development of pyrocumulonimbus clouds. Essentially, a wildfire of a strong enough size and magnitude can produce localized thunderstorms. Should these storms develop with low enough water vapor content, the end result can be virga and lightning strikes that can actually spark new fires in the surrounding areas. Likewise, if there is enough moisture content in the pyrcumulonimbus cloud, then the end-result can be rain that can kill off some, or all, of the wildfire that helped to produce it in the first place.
Wildfire in Shasta County, California on August 1st, 2014. Source: @Weather1225
In extremely rare instances, wildfires can even produce supercell thunderstorms! This was witnessed back in May 2018 over the Texas Panhandle when a substantially strong wildfire produced strong enough updrafts for a pyrocumulonimbus cloud to develop. This cloud just so happened to develop on a day with substantial low-level wind shear, low-level moisture, and instability supercell development. All that was needed was a source of lift, which in this instance came in the form of a wildfire. As a result, the cloud soon moved away from its source and evolved into a unique pyrosupercell just southeast of Amarillo, Texas.
Pyrosupercell thuderstorm just southeast of Amarillo, Texas, in May 2018. Source: Silver Lining Tours
Pyrocumulonimbus clouds are some of the most interesting cloud types out there; it can be said that these beasts are born out of the ashes, and as they evolve they can produce some of the most phenomenal and breathtaking sights on Earth. Indeed, these clouds are just one part of the dynamics and characteristics of a given wildfire, but their unique properties and evolution during such conditions are all worth the exploration.
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©2019 Meteorologist Gerardo Diaz Jr.
Lahaina Noon, a Rare Occurence for One U.S. State! (Credit: Meteorologist Jessica Olsen)
Discussion: The Hawaiian Islands are a special place that bring some of the most attractive weather year-round to its visitors and locals. Great weather, a season and location all coupled together create a rare phenomenon that only a few have ever seen, Lahaina Noon.
Lahaina Noon, a term coined by the Bernice Pauahi Bishop Museum in Honolulu, is so aptly named due to its native Hawaiian of la haina meaning “cruel sun”. With Hawaii being the only state in the US in the tropics, it experiences Lahaina Noon. This phenomenon is caused as the sun is directly overhead in a specific location or known as the sun’s zenith (subsolar polar point) travels to different locations across the earth, as the earth rotates and orbits the sun, when it hits that exact location of being overhead it creates an effect of no apparent shadow.
This rare occurrence remains often unheard of as it is limited to a specific area, this existing between the Tropic of Cancer and the Tropic of Capricorn (23.5°N and 23.5°S). This will allow for the event to occur twice per year. At the subsolar point the sun’s rays are perpendicular to the Earth’s surface. The angle between the location of the sun and an object is what casts a shadow, and when the angles are aligned (within these latitudes) the shadows appear mostly non-existent.
The next cities to experience Lahaina Noon in the United States are Hilo, on July 24th, at 12:27PM, Kailua-Kona on July 24th, 12:31PM and South Point, Hawai’i Island, July 28th, 12:29PM. For additional cities and more information on local Hawai’i astronomy in 2019 visit the Bernice Pauahi Bishop Museum.
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© 2019 Meteorologist Jessica Olsen