New Research Finds Venus’ Winds, They Are A-Changin’

 

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Venus, Earth’s hotheaded neighbor, may have more variability in its weather patterns than previously believed. Using infrared data obtained by ground-based telescopes in Hawaii and Arizona researchers have found that Venus’ mesosphere and thermosphere are less consistent in temperature than layers closer to its surface.

But first let’s talk about Venus itself.

Possibly the most inhospitable of planets in our solar system, Venus is the victim of a runaway greenhouse effect. Our neighboring world is a virtual oven… with a rocky surface baked by 800ºF temperatures and crushed beneath the weight of its own incredibly dense atmosphere, standing “sea level” on Venus would be like being 3,300 feet underwater, just in terms of pressure per square inch. And as if the heat and pressure weren’t enough, Venus’ skies are full of clouds made of corrosive sulphuric acid, lit by bolts of lightning and and whipped along by hurricane-force planetwide winds. All Earth-based probes that have ever landed there only lasted moments on the surface before succumbing to Venus’ destructive environment.

Venus is, quite literally, hellish.

Venus' south polar vortex imaged in infrared. A darker region corresponds to higher temperature and thus lower altitude. Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA.

Unlike Earth, Venus does not have much of an axial tilt. This means there’s little, if any, seasonal variation on Venus. (Actually it does have a tilt… Venus is rotated almost completely upside-down relative to its poles, and so in effect still has very little axial tilt.) And since its cloud cover is so dense and it lacks a hydrologic cycle to move heat energy around, it pretty much stays at a constant level of “extreme broil” all across Venus’ surface.

Surface weather on Venus, although unpleasant, is consistent.

Yet based on an international team’s new research this is not the case higher up in Venus’ atmosphere. A new look at old data has uncovered changing weather patterns visible in infrared light at about 68 miles (110 kilometers) above the planet’s surface in the cold, clear air above the acid clouds.

“Any variability in the weather on Venus is noteworthy, because the planet has so many features to keep atmospheric conditions the same,” said Dr. Tim Livengood, a researcher with the National Center for Earth and Space Science Education and the University of Maryland, now stationed at NASA’s Goddard Space Flight Center in Greenbelt.

Dr. Theodor Kostiuk of NASA Goddard explains further: “Although the air over the polar regions in these upper atmospheric layers on Venus was colder than the air over the equator in most measurements, occasionally it appeared to be warmer. In Earth’s atmosphere, a circulation pattern called a ‘Hadley cell’ occurs when warm air rises over the equator and flows toward the poles, where it cools and sinks. Since the atmosphere is denser closer to the surface, the descending air gets compressed and warms the upper atmosphere over Earth’s poles. We saw the opposite on Venus.”

Many factors could be contributing to Venus’ upper-atmospheric variabilities, such as interactions between opposing winds blowing around the planet at over 200 mph, giant vortexes that churn around its poles, and possibly even solar activity, like solar storms and coronal mass ejections which may create turbulence in Venus’ upper atmosphere.

“The mesosphere and thermosphere of Venus are dynamically active. Wind patterns resulting from solar heating and east to west zonal winds compete, possibly resulting in altered local temperatures and their variability over time.”

– Lead author Dr. Guido Sonnabend, University of Cologne, Germany

Artist concept of Venus' surface. (NASA)

The team also found that the temperatures of Venus’ atmosphere change over time, spanning weeks, months, years… even decades. Temperatures measured in 1990-91 are warmer than in 2009, and equatorial temperatures were even warmer in 2007.

“In addition to all these changes, we saw warmer temperatures than those predicted for this altitude by the leading accepted model,” said Kostiuk. “This tells us that we have lots of work to do updating our upper atmospheric circulation model for Venus.”

Even though Venus is compositionally similar to Earth and has a similar size as well, at some point in its history it lost all of its water to space and became the cloud-covered oven it is today. Studying Venus will help scientists learn how this may have happened and – hopefully! –  learn how to prevent the same fate from ever befalling Earth.

The paper, led by Dr. Guido Sonnabend of the University of Cologne, Germany and co-authored by Drs. Livengood and Kostiuk, appeared July 23 in the online edition of the journal Icarus.

Read more on the NASA feature article here.

Astronomy Cast Ep. 226: Weather

Hurricane observed from Earth orbit. Credit: NASA

How’s the weather? Maybe a better question is… why’s the weather? What is it about planets and their atmospheres that create weather systems. What have planetary scientists learned about our Earth’s weather, and how does this relate to other planets in the Solar System. What is the most extreme weather we know of?

Click here to download the episode.

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

Weather on the Astronomy Cast website.

What is a Warm Front?

Warm Front

[/caption]A warm front is the transition zone that marks where a warm air mass starts replacing a cold air mass. Warm fronts tend to move from southwest to southeast. Normally the air behind a warm front is warmer than the air in front of it. Normally when a warm front passes through an area the air will get warmer and more humid. Warm fronts signal significant changes in the weather. Here are some of the weather signs that appear as a warm front passes over a region.

First before the warm front arrives the pressure in area start to steadily decrease and temperatures remain cool. The winds tend to blow south to southeast in the northern hemisphere and north to northeast in the southern hemisphere. The precipitation is normally rain, sleet, or snow. Common cloud types that appear would various types of stratus, cumulus, and nimbus clouds. The dew point also rises steadily

While the front is passing through a region temperatures start to warm rapidly. The atmospheric pressure in the area that was dropping starts to level off. The winds become variable and precipitation turns into a light drizzle. Clouds are mostly stratus type clouds formations. The dew point then starts to level off.

After the warm front passes conditions completely reverse. The atmospheric pressure rises slightly before falling. The temperatures are warmer then they level off. The winds in the northern hemisphere blow south-southwest in the northern hemisphere and north-northwest in the southern hemisphere. Cloudy conditions start to clear with only cumulonimbus and stratus clouds. The dew point rises then levels off.

Knowing about how warm fronts work gives a better understanding of how pressure systems interact with geography to create weather. Looking at warm fronts we learn that they are the transition zone between warm humid air masses and cool, dry air masses. We know that these masses interact in a cycle of rising and falling air that alters the pressure of atmosphere causing changes in weather.

We have written many articles about warm front for Universe Today. Here’s an article about cyclones, and here’s an article about cloud formations.

If you’d like more info on warm front, check out NOAA National Weather Service. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Reference:
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/af/frnts/wfrnt/def.rxml

How Does Fog Form?

How Does Fog Form

Fog is a natural weather conditions that can cause visibility to become zero. It can cause accidents on normally safe roads and is such a serious weather condition that schools delay the start of the day until the sun burns it off. So how does fog form? First it is important to understand that fog is basically a cloud on the ground. This means like clouds it is a collection of tiny water droplets formed when evaporated water is cooled. The way it is cooled determines how fog is formed.

The first way that fog is formed is by infrared cooling. Infrared cooling happens due to the change of seasons from summer to fall and winter. During the summer the ground absorbs solar radiation. As air passes over it is made warm and moist. When the seasons change this mass of warm moist air collides with the cooler that is now prevalent. This cause is the water vapor in the air mass to condense quickly and fog is formed. This fog is often called radiation fog due to the way it forms. This kind is the most common type of fog. It also happens when an unseasonable day of warm weather combined with high humidity is followed by dropping temperatures

The next way that fog forms is through advection. Advection is wind driven fog formation. In this case warm air is pushed by winds across a cool surface where it condenses into fog. There are also other kinds of fog like hail fog or freezing fog. Each of these conditions is where condensed water droplets are cooled to the point of freezing. There is also fog formed over bodies of water. One type is sea smoke. This is a type of fog that forms when cool air passes over a warm body of water or moist land.

In general we see that fog is formed whenever there is a temperature difference between the ground and the air. When the humidity is high enough and there is enough water vapor or moisture fog is sure to form. However the kind of fog and how long is last and its effects will depends on the different conditions mentioned. One interesting kind of fog actually helps to make snow melt faster.

We have written many related articles for Universe Today. Here’s an article about stratus clouds, and here’s an article about acid rain.

If you’d like more info on fog, check out NOAA National Weather Service website. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Reference:
http://www.crh.noaa.gov/jkl/?n=fog_types

Where do Hurricanes Occur?

View of Hurricane Ike From Space Station

What is a hurricane? Well, a hurricane is a tropical cyclone that occurs in the North Atlantic Ocean or the Northeast Pacific Ocean and remains east of the International Dateline. Tropical cyclones are characterized by a large low pressure center and numerous thunderstorms. These produce strong winds and heavy rain. These cyclones feed on heat released when moist air rises causing condensation of the water vapor that is contained in the moist air. These storms are fueled by a different heat mechanism than other cyclonic windstorms(nor’easters, polar lows, and European windstorms). They are classified as a warm core storm system.

All tropical cyclones are areas of low atmospheric pressure. As a matter of fact, the pressures recorded at the center of tropical cyclones are among the lowest that occur at sea level. A hurricane is characterized and driven by the release of large amounts of latent heat of condensation(water vapor condenses as it moves upward). This heat is distributed vertically around the center of the storm, so, except at the surface of water, it is warmer inside the cyclone than it is outside. At the center of the hurricane is an area of sinking air. If this area is strong enough, it can develop into a large eye. Weather in the eye is normally calm and free of clouds, but the surface of the sea may be tossing violently. The eye is normally circular in shape, and may range in size from 3 km to 370 km in diameter.

While a tropical cyclone’s primary energy source is the release of the heat of condensation, solar heating is the initial source of that evaporation. An initial warm core system(an organized thunderstorm complex) is necessary for the formation of a tropical cyclone, but a large flux of energy is needed to lower atmospheric pressure. The influx of warmth and moisture from the underlying ocean surface is critical for tropical cyclone strengthening and most of it comes from the lower 1 km of the atmosphere. Condensation leads to higher wind speeds. These faster winds and the lower pressure associated with them cause an increase in surface evaporation and more condensation. This positive feedback system continues and feeds the hurricane until the conditions for hurricane formation are gone. The rotation of Earth causes the system to spin,(the Coriolis effect) which gives it a cyclonic appearance and affects its trajectory.
Tropical cyclones are distinguished by the deep convection that fuels them. Since convection is strongest in the tropics it defines the initial domain of the tropical cyclone. To continue to feed itself a tropical cyclone must remain over warm water. When a tropical cyclone passes over land, it is cut off from its heat source and its strength diminishes rapidly. The passage of a tropical cyclone over the ocean can cause the upper layers of the ocean to cool substantially, which can influence subsequent cyclone development. Scientists at the National Center for Atmospheric Research in the US estimate that a tropical cyclone releases heat energy equal to 70 times the world energy consumption, 200 times the worldwide electrical generating capacity, or the same as exploding a 10 megaton nuclear bomb every 20 minutes.
Well, there you have the answer to what is a hurricane. It is a tropical nightmare, but if humans could somehow harness that energy we would never need fossil fuels again.

We have written many articles about hurricanes for Universe Today. Here’s an article about human influences generating more hurricanes, and here’s a NASA video of Hurricane Bill.

If you’d like more info on hurricanes, check out Visible Earth Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

What Are Tornadoes?

Tornado at Union City, Oklahoma Credit: NOAA Photo Library

Also known as a twister, a tornado is a rotating column of air that can cause a tremendous amount of damage on the ground. Tornadoes can very in size from harmless dust devils to devastating twisters with wind speeds greater than 450 km/h.

A tornado looks like a swirling funnel of cloud that stretches from bottom of the clouds down to the ground. Depending on the power of the tornado, there might be a swirling cloud of debris down at the ground, where it’s tearing stuff up. Some tornadoes can look like thin white ropes that stretch from the sky down to the ground, and only destroy a thin patch of ground. Others can be very wide, as much as 4 km across, and leave a trail of destruction for hundreds of kilometers.

Tornadoes appear out of special thunderstorms known as supercells. They contain a region of organized rotation in the atmosphere a few kilometers across. Rainfall within the storm can drag down an area of this rotating atmosphere, to bring it closer to the ground. As it approaches the ground, conservation of momentum causes the wind speed to increase until it’s rotating quickly – this is when tornadoes cause the most damage. After a while the tornado’s source of warm air is choked off, and it dissipates.

When a tornado forms over water, it’s called a waterspout. These can be quite common in the Florida Keys and the northern Adriatic Sea. Most are harmless, like dust devils, but powerful waterspouts can be driven by thunderstorms and be quite dangerous.

Scientists have several scales for measuring the strength and speed of tornadoes. The most well known is the Fujita scale, which ranks tornadoes by the amount of damage they do. A F0 tornado damages trees, but that’s about it, while the most powerful F5 tornado can tear buildings off their foundations. Another scale is known as the TORRO scale, which ranges from T0 to T11. In the United States, 80% of tornadoes are F0, and only 1% are the more violent F4 or F5 twisters.

Although they can form anywhere in the world, tornadoes are mostly found in North America, in a region called Tornado Alley. The United States has the most tornadoes of any country in the world; 4 times as many as the entire continent of Europe. The country gets about 1,200 tornadoes a year.

We have written many articles about the tornado for Universe Today. Here’s an article about the biggest tornado, and here’s an article about how tornadoes are formed.

If you’d like more info on tornadoes, check out the National Oceanic & Atmospheric Administration (NOAA) Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

What is Causing Weather Extremes in 2010?

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Massive rains in Pakistan, China and Iowa in the US. Drought, heat and unprecedented fires in Russia and western Canada. 2010 is going down as the year of crazy, extreme weather. Is this just a wacky year or a trend of things to come? According to meteorologists, unusual holding patterns in the jet stream in the northern hemisphere are to blame for the extreme weather in Pakistan and Russia. But also, the World Meteorological Organization and other scientists say this type of weather fits patterns predicted by climate scientists, and could be the result of climate change.

“All these things are the kinds of things we would expect to happen as the planet warms up,” said Tom Wagner, a NASA scientist who studies the cryosphere, during an interview on CNN on August 11. “And we are seeing that the planet is warming about .35 degrees per decade. Places like Greenland are warming even faster, like 3.5 degrees per decade. And all these events from heat waves to stronger monsoons, to loss of ice are all consistent with that. Where it gets a little tricky is assigning any specific event to say, the cause of this event is definitely global warming, that is where we get to the edge of the research.”

“This weather is very unusual but there are always extremes every year,” said Andrew Watson from the University of East Anglia’s Environmental Studies. “We can never say that weather in a single year is unequivocal evidence of climate change, if you get many years of extreme weather then that can point to climate change.”

The Intergovernmental Panel on Climate Change (IPCC) has long predicted that rising global temperatures would produce more frequent and intense heat waves, and more severe rainfalls. In its 2007 report, the panel said these trends have already been observed, with an increase in heat waves since 1950, for example.

NOAA measurements show that the combined global surface temperatures for June 2010 are the warmest on record, and Wagner said there are larger conclusions to be drawn from the definite global warming trend. “We are seeing things that haven’t really happened before on the planet, like warming at this specific rate. We think it is very well tied to increasing carbon dioxide in the atmosphere since the late 1800’s caused by humans.”

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Source: NOAA)

Graphs on NASA’s climate website show an undeniable rise in global temperatures, sea levels, and carbon dioxide levels. See more of these graphs here.

“Not just over 10 years, but we have satellites images, weather station records and other good records going back to the late 1800’s that tells us all about how the planet is warming up,” Wagner said. “Not only that but we have evidence from geologic records, ice cores, and sediment cores from ocean cores. All of this feeds together to show us how the planet is changing.”

Asked if the cycle can be reversed, Wagner replied, “That is the million dollar question. One thing we have to think about is that the planet is changing and we have to deal with that. Ice around Antarctica and Greenland is melting. Sea level is rising right now at 3 millimeters a year. If you just extrapolate that to 100 years, it will rise to at least a foot of sea level rise. But there is the possibility it could be more than that. These are the types of things we need to think about and come up with mitigation strategies to deal with them. We’re doing the research to try and nail down these questions a little more tightly to see how much sea level is going to rise, how much temperatures are going to rise and how are weather patterns going to change.”

Reducing emissions is one thing that everyone can do to help protect the planet and the climate, and climate experts have been saying for years that there needs to be sharp cutbacks in emissions of carbon dioxide and other heat-trapping gases that go into the atmosphere from automobiles, power plants, and other fossil fuel-burning industrial and residential sources.

In the news this week was the huge ice chunk coming loose from a Greenland glacier. Not only is this an indication of warming water, but other problems could develop, such as the large ice chunks getting in the way of shipping lanes or heading towards oil rigs. The high temperatures and fires in Russia are affecting big percentage of the world’s wheat production, and could have an effect on our food supply this coming year.

Not only that, but the wildfires have created a noxious soup of air pollution that is affecting life far beyond just the local regions, JPL reports. Among the pollutants created by wildfires is carbon monoxide, a gas that can pose a variety of health risks at ground level. Carbon monoxide is also an ingredient in the production of ground-level ozone, which causes numerous respiratory problems. As the carbon monoxide from these wildfires is lofted into the atmosphere, it becomes caught in the lower bounds of the mid-latitude jet stream, which swiftly transports it around the globe.

Two movies were created using continuously updated data from the “Eyes on the Earth 3-D” feature, also on NASA’s global climate change website. They show three-day running averages of daily measurements of carbon monoxide present at an altitude of 5.5 kilometers (18,000) feet, along with its global transport.

And in case you are wondering, the recent solar flares have nothing to do with the wildfires — as Ian O’Neill from Discovery space deftly points out.

Sources: CNN, AP, JPL , SkyNews

Cold as Hell with a Chance of Dust Storms: Weather Movies from Mars

If you think about it, those hypnotizing patterns of swirling clouds you see in TV weather reports are pretty amazing: satellites let us see what’s happening in the skies all over the world. But these days, that kind of global vision even goes beyond the Earth. The Mars Reconnaissance Orbiter makes daily weather observations of the Red Planet, and mission scientists regularly compile the pictures into movies that are available online. The result is that anyone can follow along as fierce dust storms rage across the plains of Mars, clouds cling to the peaks of towering volcanoes and polar ice advances and retreats.

On board the MRO is a wide-angle camera called the Mars Color Imager (MARCI) that scans the face of Mars in both visible and ultraviolet light. MARCI views Mars from pole to pole, snapping dozens of images every day that are combined into a global map with resolution comparable to weather satellites at home.

This daily weather report helps Mars explorers understand day-to-day events, as well as seasonal and annual changes on the Red Planet. Sometimes the weather watch also gives rover drivers a crucial warning when a storm might be headed in the direction of Spirit or Opportunity.

The weather images can be striking and intriguing. This animation shows the south pole of Mars during a period of about a month earlier this year, when storms raged along the retreating edge of frost in the polar cap. You can see giant, swirling clouds of dust, as well as the changing shape of the cap as it shrinks with the approach of Summer.

Malin Space Science Systems is the firm that built and operates MARCI for NASA’s Jet Propulsion Laboratory. They post weekly movies that show a spinning, global view of the most recent Martian weather. You never know what you’ll see each week, but a careful look often turns up water ice clouds, wind storms or the giant canyon Valles Marineris filled to the brim with dust.

The descriptions that Malin scientists write to accompany each movie are fascinating. They sound both as exotic as a science fiction novel–and as routine as your local weatherman’s report on the evening news. One sample:

“A large dust storm moved south down the Acidalia/Chryse/Xanthe corridor, partially spilling into eastern Valles Marineris at the beginning of the week. From there the storm moved over Thaumasia and Argyre, picking up intensity as it moved into the subtropics of Aonia and Icaria/Daedalia… Dust storms and water-ice clouds also formed in the northern mid-latitudes, with more notable activity occurring over Deuteronilus and Utopia. The increased amount of dust activity on the planet has created a haze that lingers in the atmosphere and has caused skies over both Opportunity and Spirit to be hazy during the past week.”

That’s why Mars fascinates. It’s an alien world that in some ways is tantalizing similar to home.

MARCI will be turned back on in early December after a hiatus of a few months. Previous weather movies are still online.

How Close Was That Lightning to the Shuttle?

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If you’re wondering why the first launch attempt for space shuttle Discovery was scrubbed early Tuesday morning, here’s your answer. Yikes! But what a gorgeous picture! And of course, the second launch attempt early Wednesday morning was called off when instrumentation for an 8-inch fill and drain valve on the shuttle’s external tank indicated the valve had failed to close. But yesterday, the valve functioned correctly five times during launch pad tests, NASA said. That means NASA will likely go ahead with a launch attempt at 04:22 GMT (12:22 a.m. ET) on Friday. But the anomaly remains unexplained, so it will be up to the mission management team to decide if the shuttle can fly as is, or if engineers need to know more about the issue. The decision won’t be made, however until the MMT meets Thursday afternoon, just hours before the scheduled liftoff time. As the saying goes, there’s a million parts on the shuttle and if only one is not working….

UPDATE: Launch now is targeted for no earlier than 11:59 p.m. Friday, Aug. 28, to allow engineers more time to develop plans for resolving the issue with the valve.

See below for a close-up of the lightning shot, to see how close it actually came to the shuttle.

Lightining strikes close to Discovery on the launchpad on Aug. 25, 2009. Credit: NASA/Ben Cooper.  Click image for access to larger version.
Lightining strikes close to Discovery on the launchpad on Aug. 25, 2009. Credit: NASA/Ben Cooper. Click image for access to larger version.

Discovery’s 13-day mission will deliver more than 7 tons of supplies, science racks and equipment, as well as additional environmental hardware to sustain six crew members on the International Space Station. The equipment includes a freezer to store research samples, a new sleeping compartment and the COLBERT treadmill. The mission is the 128th in the Space Shuttle Program, the 37th flight of Discovery and the 30th station assembly flight.

Hat Tip to absolutespacegrl on Twitter!