۩۞۩ FACE OF WAR۩۞۩
دانلود-عکس-مطلب و...۩۞۩ FACE OF WAR۩۞۩
دانلود-عکس-مطلب و...گرمایش زمین به احتمال زیاد کار بشر است
'هیات بین المللی بررسی تغییرات آب و هوایی' (IPCC) می گوید تغییرات جوی که در سراسر 
جهان مشاهده می شود به احتمال خیلی زیاد ناشی از عواملی است که بشر در آنها دست دارد.منظور "آی پی سی سی" از "احتمال خیلی زیاد" رقمی بیش از 90 درصد است.
این نهاد علمی درحال نهایی کردن مواضع خود در مورد برخی مسائل کلیدی به خصوص پیش بینی ها درباره بالا آمدن سطح آب ها است که آنها را طی یک گزارش عمده منتشر خواهد کرد.
اما مطالعه تازه ای که شب پیش از انتشار گزارش نهایی فاش شد نشان می دهد که گزارش های قبلی این گروه احتمالا بیش از حد محافظه کارانه بوده است.
به گزارش بی بی سی، پژوهش های یک گروه بین المللی از دانشمندان نتیجه گیری می کند که افزایش دما و سطح دریاها به اندازه حداکثر پیش بینی شده در گزارش سال 2001 "آی پی سی سی" یا بالاتر از آن بوده است.
نخستین بخش گزارش سال 2007 این گروه روز جمعه در پاریس منتشر خواهد شد.
طبق الگوهای کامپیوتری که ذوب شدن یخ های قطبی در آن محاسبه نشده است، در قرن جاری سطح آبها تا نیم متر بالا خواهد آمد.
محاسبات دیگر احتمال ذوب شدن تدریجی صفحات بزرگ یخی قطب را در بر می گیرد. هنوز در انتخاب میان این دو الگو میان دانشمندان اتفاق نظر وجود ندارد.
درباره میزان گرمایش نیز هنوز حکمی قطعی صادر نشده، اما دانشمندان بر آنند که تا پایان قرن آب و هوای کره زمین از 2 تا 4.5 درصد افزایش خواهد داشت.
دانشمندانی که در نشستی در این زمینه در پاریس گرد آمده اند قصد دارند نتیجه داده های هزاران کار پژوهشی را درباره دانش دگرگونی های آب و هوایی منتشر کنند.
کنفرانس پاریس به دگرگونی های جوی، عوامل مؤثر در آنها و شیوه مقابله با آنها و همچنین نحوه کاستن از اثرات گازهای گلخانه ای می پردازد.
دولتمردان و دانشمندان و گروه های مدافع محیط زیست با توجهی فزاینده کنفرانس علمی را دنبال می کنند زیرا انتظار می رود به بسیاری پرسش ها و کنجکاوی ها پاسخ بگوید.
گروه برنامه محیط زیست وابسته به سازمان ملل متحد از نایروبی گفته است که گزارش کنفرانس باید به بسیاری گفتگوها درباره عوامل اصلی گرمایش زمین پایان دهد.
برخی از کارشناسان و دانشمندان نظر داده اند که گرمایش زمین در وقوع توفان ها و سیلاب های قوی سال های گذشته دخیل بوده است. در درستی این نظر همچنان اختلاف نظر وجود دارد، اما احتمال دارد که کنفرانس بررسی تغییرات آب و هوایی پاریس به آن اعتبار بیشتری بدهد.
موجودیت و عدم موجودیت ( 2 )
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181 Things To Do On The Moon
سلام
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February 2, 2007: If you woke up tomorrow morning and found yourself on the moon, what would you do? NASA has just released a list of 181 good ideas.
Ever since the end of the Apollo program, "folks around the world have been thinking about returning to the moon, and what they would like to do there," says Jeff Volosin, strategy development lead for NASA's Exploration Systems Mission Directorate. Now, NASA is going back; the agency plans to send astronauts to the Moon no later than 2020. "So we consulted more than 1,000 people from businesses, academia and 13 international space agencies to come up with a master list of 181 potential lunar objectives."
For example, the moon could be a good location for radio astronomy. A radio telescope on the far side of the Moon would be shielded from Earth's copious radio noise, and would be able to observe low radio frequencies blocked by Earth's atmosphere. Observations at these frequencies have never been made before and opening up a window into this low frequency universe will likely lead to many exciting new discoveries.
Right: A radio telescope on the moon uses a crater to support its giant primary dish. Artist's concept by Pat Rawlings. [More]
The moon would also be an excellent place to study the high-energy particles of the solar wind, as well as cosmic rays from deep space. Earth's magnetic field and atmosphere deflect many of these particles, so even satellites in low-Earth orbit can't observe them all. The moon has virtually no atmosphere, and it spends most of its 28-day orbit outside of Earth's magnetosphere. Detectors placed on the moon could get a complete profile of solar particles, which reveal processes going on inside the sun, as well as galactic cosmic radiation from distant black holes and supernovas.
Bonus: These particles are trapped by lunar regolith, the layer of crushed rock and dust covering the moon's surface. This means that lunar regolith contains a historical record of solar output: core samples could tell us about changes in solar output over billions of years. "We believe that the moon's preservation of this solar record is unique and can provide us with insights on how past fluctuations in the solar output have affected, for example, the history of life on Earth," says Volosin. In particular, it could shed light on the extent to which solar variability and galactic cosmic radiation influence climate change.
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But the moon would be far more than just a platform for scientific instruments gazing into space. The moon itself is a scientific gold mine, a nearby example of planetary formation largely unaltered by the passage of time. Some scientists call it "a fossil world." The moon is a small, non-dynamic planetary body and its interior state is largely preserved since the early days of solar system history. Studying its interior would tell scientists a lot about how a planet's internal layers separate and solidify during planetary formation.
Even something as simple as establishing the dates when various craters on the moon were formed can provide us with a unique picture of how the flux of meteoroids in the vicinity of Earth has changed over time. (For more information see Science@NASA's "The Moon is a Harsh Witness.") This impact history is lost on Earth by the constant renewal of the crust but on the moon it is intact, rich with clues to periods in the past when an increase in bombardment may have affected the climatic history of Earth and even the evolution of life.
Science accounts for only about a third of the 181 objectives, however. More than half of the list deals with the many challenges of learning to live on an alien world: everything from keeping astronauts safe from radiation and micrometeors to setting up power and communications systems to growing food in the airless, arid lunar environment.
"We want to learn how to live off the land and not depend so much on supplies from Earth," says Tony Lavoie, leader of NASA's Lunar Architecture Team (Phase 1) at the Marshall Space Flight Center.
Right: Two astronauts go prospecting with a robotic sidekick. [More]
Astronauts would face the same problems on a manned mission to Mars, so much of the experience gained on the moon would carry over when NASA eventually sends people to the Red Planet.
The moon could also provide some creative commercial opportunities: lunar power from solar cells, protected data archives, mining of lunar metals, and research under conditions of low gravity and high vacuum, to name a few. In fact, mining the moon may eventually yield rocket propellant that could be sold to commercial satellite operators to access and service their satellite assets in Earth orbit. Beyond charging space tourists for a chance to visit the moon, lunar entrepreneurs might host special television events from the moon to boost publicity, or place a remote-controlled rover on the moon. People back on Earth could pay to take turns controlling the rover from their Internet-connected computers, letting them take a virtual drive across the moon's crater-pocked surface. In short, let your imagination be your guide!
Not all of the ideas on the list will necessarily happen. From the master list of 181, NASA currently is selecting the a smaller number of high priority goals for its initial return to the moon. Other goals could be considered by other space agencies or private entrepreneurs who have an interest in exploring the moon. NASA continues to receive input from scientists at space agencies and universities around the world, the list itself is still evolving and expanding.
در عالم پر ازدحام: تنها یا ... !!!؟؟؟
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موجودیت و عدم موجودیت ( 1 )
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مدل کیهانی VMR-PCR
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طرز کار راکت های فضایی
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