Where Is the Hottest Place on Earth_ _ Feature Articles.pdf

8/11/2019 Where Is the Hottest Place on Earth_ _ Feature Articles.pdf

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6/16/2014 Where Is the Hottest Place on Earth? : Feature Articles

http://earthobservatory.nasa.gov/Features/HottestSpot/page2.php

What Does It Mean to be Hot?

On the warmest summer days, you may hear someone say: its a

hundred degrees in the shade. Its an old-fashioned phrase with an

unintended kernel of insight.

Air temperatures must be measured out of direct sunlight because the

materials in and around the thermometer can absorb radiation and affect

the sensing of heat. You feel this with your own body: if you stand in

direct sunlight, you feel warmer because your skin is being heated by

both the air and by the radiant energy from the Sun.

To make an air temperature reading according to the World

Meteorological Organization standard(PDF), a thermometer must be

situated 1.2 to 2 meters off the ground and shielded from direct sun

though it cannot be placed in the shade of a building, mountain, or tree

either.

Direc t sunlight can heat

surface s well above airtemperature. On one late winter

afternoon when the air was 54F

(12C), shaded areas ranged from

4046F (4.08.0C), while sunny

spots we re from 5666F (13

19C). (NASA photograph by

Robert Simmon.)
http://www.wmo.int/pages/prog/www/IMOP/publications/CIMO-Guide/CIMO%20Guide%207th%20Edition,%202008/Part%20I/Chapter%202.pdf


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MODIS measures something different: land skin temperature. LST is ameasure of heating of the land surfacewhere solar energy is absorbed

and re-emittedand it is often significantly hotter than air temperature. If

youve ever walked barefoot across hot sand or pavement on a summer

day, you know the difference. The surface beneath your feet feels much

hotter than the air around your head.

Scientists first measured that difference in June 1915. Around the same

time that the Death Valley record air temperature was measured, an

analysis of the temperature conditions of air and soil was conducted in

the desert near Tucson, Arizona, Mildrexler explains. In the midday sun,

the temperature 0.4 centimeters below the soil surface was 71.5C

(160.7F). The air temperature, measured four feet above the ground, was

42.5C (108.5F).

Air temperatures, on the one hand, are moderated by circulationboth

Accurate air temperature

readings must be taken with

thermometers that are carefully

shielded from direct sunlight.

(Photograph2006 Richard

Allaway.)

Dark pebbles he lp make Irans

Lut Desert the hottest place on
http://www.geographyalltheway.com/http://www.flickr.com/photos/geographyalltheway_photos/3042177780/


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the rising and sinking of air masses into the atmosphere, and the

horizontal movement of winds across the landscape. Moisture also

regulates how much heat can be stored in the air. The value of the air

temperature measurement, as opposed to land surface temperature, is

that it is what the human body, a building, or an eco system are fee ling,

says Stuart Gaffin, a climate researcher at Co lumbia University and NASAs

Goddard Institute for Space Studies. Air temperatures largely dictate our

thermal comfort level.

On the other hand, land skin temperatures reflect the pure heating of a

parcel of ground by radiation from the sun, the atmosphere, and other

heat flows. Therefore, the ho ttest LSTs are likely to occur where the

skies are clear, the soil is dry, and the w inds are light. The final ingredient

is the composition of the land surface. It should absorb most light and

reflect littlethat is, have a low albedoand it should not conduct heat

very well. Rocky deserts offer the perfect combination.

In their analysis, Running, Mildrexler, and Maosheng Zhao scrutinized

global MODIS measurements o f LST from 2003 to 2009, paying special

attention to where the hottest satellite temperatures matched up w ith

the ideal terrain. To reveal the hottest spot on Earth, Mildrexler notes,

we focused on barren areas and sparsely vegetated, open shrublands.

The formula brought them to the Lut Desert in Iran. And to the badlands

of Queensland, Australia. And to the Flaming Mountain.

Earth. (Photograph 2005 Jafar

Sabouri, Geological Survey of

Iran.)

The dark surface of the

Shanshan dune field absorbs

sunlight more strongly than the

adjacent Flaming Mountain,

making it much hotter. (NASA

images by Jesse Allen and

Robert S immon, using Landsat 7

data from the USGS Global

Visualization Viewer.)
http://glovis.usgs.gov/http://gsi.ir/Main/Lang_en/ind


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In five of the seven years2004, 2005, 2006, 2007, and 2009the

highest surface temperature on Earth was found in the Lut Desert. The

single highest LST recorded in any year, in any region, occurred there in

2005, when MODIS recorded a temperature of 70.7C (159.3F)morethan 12C (22F) warmer than the official air temperature record from

Libya.

But the Lut was not the hottest spot every year. In 2003, the satellites

recorded a temperature of 69.3C (156.7F)the second highest in the

seven-year analysisin the shrublands of Queensland. And in 2008, the

Flaming Mountain got its due, with a yearly maximum temperature of

66.8C (152.2F) recorded in the nearby Turpan Basin.

200309

Seven years of satellite

temperature data show that the

Lut Desert in Iran is the hottest

spot on Earth. The Lut Desert

was hottest during 5 of the 7

years, and had the highest

temperature overall: 70.7C

(159.3F) in 2005. (NASA maps by

Jesse Allen and Robert Simmon,

using MODIS data from

Mildrexle r et al., 2011.

|Introduction Whats the Value of Land Skin Temperature?
http://earthobservatory.nasa.gov/Features/HottestSpot/page3.phphttp://earthobservatory.nasa.gov/Features/HottestSpot/page1.phphttp://dx.doi.org/10.1175/2011BAMS3067.1

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Where Is the Hottest Place on Earth_ _ Feature Articles.pdf