Feeds:
Posts
Comments

Posts Tagged ‘heat’

Summer daylight and heat cycle by USA Today

 

 

by Erik Baard

 

A kid waiting to kayak at the Clearwater Festival last Solstice weekend asked me, “If this is the longest day of the year, then why isn’t it the hottest?” It’s a logical question, and I guess a common one. The incomparable Joe Rao addressed it in his New York Times astronomy blurb last week, and USA Today explored the question as well. The graphic above comes from USA Today.

 

In short, if Earth lacked an atmosphere, then surface temperature, apart from heat retained by rocks, would correlate with sun exposure. But our relatively stable atmosphere slowly and steadily receives energy from sunlight over the course of the spring and summer, as days lengthen. That energy, which we feel as heat, builds higher and higher until reaching its peak in July and early August.

 

I suppose an economist might call day length a leading indicator of summer, whereas as temperature is a lagging indicator. Swimmers and boaters (who are perpetually potential swimmers) know that this phenomenon of delay is even more pronounced with water temperatures.

 

Of course both air and water move around, so there’s a good bit of chaos and complexity to the fluid dynamics that make for summer weather and those late night skinny dips in open water that feel as warm as a bathtub. But the principle of heat retention is a far more powerful truth than its exceptions.

 

I’m also reminded of my good friend, David Grinspoon (with whom, for the record, I’ve never skinny-dipped), who joined us with comments about the Orion Nebula for the very first essay on Nature Calendar. He’s an astrobiologist (with an Earthly incarnation as a rhythm guitarist) with prestigious Mars and Venus robotic probe science assignments from both NASA and the European Space Agency, and serves as the curator of astrobiology at the Denver Museum of Science and Nature. He’s devoted much of his career to the planet Venus. He notes that if there was intelligent groundling life on Venus, it won’t see dominant temperature zones as we see them, corresponding to latitude, but instead look skyward to temperate altitudes. This is because Venus has an atmosphere that’s so dense, and therefore conductive, that heat overloads long ago seeped across all geographic areas. The surface is now isothermic, meaning that temperatures at the poles and the equator are the same. It’s gotten so hot there, due to a greenhouse effect gone into overdrive, that David postulates Venusian life would prefer a cloud habitat

 

Of course, our cities perversely punish themselves, with air conditioners dumping extra heat into the dense local ecosystem through their exhaust, building electrical wires, regional transmission lines, and the power plants required to power them. Makes you wonder if there’s intelligent life on Earth.

Advertisements

Read Full Post »

Panting hawk in Flushing, Queens.

 

A glance at this red-tailed hawk brings to mind its famed cry, which Cornell University notes is dubbed into the beaks of hawks and eagles in movies and television shows ad infinitum. In reality you’re seeing a hawk pant.

 

 

The iconic Unisphere in Flushing Meadows-Corona Park is home to a pair of hawks whose nest is in the Indian Ocean, so to speak. But that exposure, perhaps worsened by glaringly reflective metal, drove this bird down below the shade of the tree canopy. My kayaking and biking buddy, Richard Furlong of LaGuardia Community College’s ESL program, found himself ten feet below this hawk while in the park for the Tour de Queens and took these shots (click to enlarge).  

 

Red-tailed hawk near the Unisphere. Photo by Richard Furlong.

 

Another friend, Emmanuel Fuentebella, captured the other hawk in these photos as he (I believe, since it looked smaller) watched the crazily busy skateboarding circle at the base of the Unisphere.

 

red-tailed hawk in the Unisphere. Photo by Emmanuel Fuentabella.

 

Red-tailed hawk in Unisphere. Photo by Emmanuel Fuentabella.

 

I was shocked at the idea of a hawk scooting under leaf cover to close to the ground, even though a friendly Queens knitter, Helen, told me of a red-tailed hawk living at a local courthouse that was equally unphased by human company. It’s still commonly believed that red-tailed hawks will soar to cool down, with temperatures dropping with rising altitudes. Skepticism is building, as shade seeking is far more apparent. Also, soaring is an effective territorial and mating display, explaining many hours spent aloft while not hunting.

 

 

Other bloggers (http://www.fordham.edu/politicalsci/profs/fleisher/NYC_hawks.html, http://adevolution.wordpress.com/2008/04/26/update-animal-profile-red-tailed-hawks-of-flushing-meadows/) have noted that the Unisphere hawks are very attentive to their nests, giving rise to hopes for a new generation. I worry that the heat, which is LOUDLY breaking in a storm as I type, might endanger eggs or hatchlings.

 

Ferruginous hawks, a more heat-adapted North American desert species, suffers markedly higher infant mortality rates as temperatures rise. Though nests seem to be located regardless of shading, adults and hatchlings alike seek shade. Strangely, the first motivation for fledglings to leave the nest appears to be to find shade (not to mothers everywhere – send junior packing by turning off the air conditioner). Another surprising aspect of ferruginous hawks’ is that their remarkably large gapes might be an adaptation to pants more effectively in addition to consuming large prey.

 

As a small side note, hawks’ young were found to die from heat stress in greater numbers when ill fed. I wonder if there’s a compounding problem here, with potential prey hunkering down, even under ground, to remain cool while riding out heat waves.

 

Let’s hope for the best, and watch and learn.

Read Full Post »