Here's Your World Today, Explained
Here's a true color look at our home planet this afternoon; the western half of it, anyway. It's beautiful, and there are lots of really cool features you can see from space today. Let's take a closer look at our pale blue dot.
(Note: here's a link to the latest full-disk image from NASA—the images in this post were taken from the 17:45 UTC scan.)
A) Scary Arctic Blast of Doom
This feature is the week's big weather story—the "A" is located right over the center of the low pressure system that's causing so much grief for people who hate cold weather. The storm formed over the central Plains the other day and booked it towards the Great Lakes, dumping one to two feet of snow across the Upper Midwest as it drags cold air down to the Gulf of Mexico.
The cold front—seen roughly along the strip of clouds from the Great Lakes to Mexico—hits very abruptly. Yesterday afternoon, the cold front created a brutal temperature gradient across Iowa as it passed through the state. The southeastern half of Iowa could wear t-shirts as temperatures were in the 70s, while the northwestern part of the state had to bundle up as temperatures plummeted into the 20s with wind chills approaching single digits.
The front will continue moving east over the next couple of days, eventually dropping temperatures into coat territory for everyone east of the Rockies.
B) The Polar Flortex
I wrote a post yesterday explaining the storm system off the Florida coast that looked eerily reminiscent of a hurricane. The storm, which is your run-of-the-mill extratropical cyclone, quickly started to lose its hurricane look on radar, but compensated for it by developing a wonderful comma-head appearance on satellite imagery.
The storm will move out to sea over the next few days, posing no further threat to the U.S.
C) Tropical Disturbance Near Mexico
There's a tropical disturbance sitting off the western coast of Mexico, bringing heavy rainfall to areas between Manzanillo and Puerto Vallarta. The National Hurricane Center noted in its 2:00 PM advisory that the storm has a low chance of developing due to strong upper-level wind shear.
D) Roll Clouds
If you look closely, at the tip of each arrow is a sharp, tubular-shaped patch of clouds sitting over the middle of the Atlantic Ocean. These are roll clouds, and they're common over the ocean after thunderstorm complexes collapse and dissolve. When a thunderstorm collapses, its downdraft overpowers the updraft, allowing all of the rain to precipitate out of the storm, which drags cold air to the surface.
When the cold air hits the surface, it spreads out in all directions, creating an outflow boundary or gust front (the burst of cool wind you feel ahead of a thunderstorm). Features known as "roll clouds"—which appear as long, horizontal cloud tubes when viewed from the ground—often form along the leading edge of these outflow boundaries over the ocean.
E) Saharan Dust
The fuzzy, hazy appearance of the atmosphere over and off the western coast of Africa is dust and sand blowing from the Sahara Desert. These dry bursts of dust coming off of Africa are responsible for killing many a hurricane season, including the one this year.
F) The ITCZ
The long, thick strip of clouds extending from Africa to the middle of the Atlantic Ocean is intense thunderstorm activity that exists as a result of the Intertropical Convergence Zone, or ITCZ. The ITCZ is the area where trade winds from the north and the south converge near the equator. Flights flying from the northern to the southern hemisphere often have to fly through storms along the ITCZ, producing uncomfortable turbulence.
G) Thunderstorms over Paraguay
It's spring in the southern hemisphere, and we in the United States know all too well that spring comes with some rocking thunderstorms. The airport in Asunción—the capital of Paraguay—reported a thunderstorm at 2:00 PM EST, with an air temperature of 72°F and 100% humidity. That makes the dew point 72°F, which is extremely uncomfortable, especially when it's raining.
When you're shivering, remember that you could be elsewhere sweating instead. It's easier to warm up than it is to cool down.
H) Storms Over the Amazon
Thunderstorms over the Amazon are a daily occurrence because of the region's ample moisture and tropical temperatures. It's really cool to look at clouds over the Amazon during the heat of the day—the clouds form over the rainforest, but skies directly over bodies of water (rivers, lakes, bays) are completely clear. It's a great lesson in convection.
The world is a beautiful place, and the novelty of looking at a current image of it from space at the click of a mouse will never wear off.
[Images: NASA/GOES, with notes by the author]