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INTRODUTION
الارض، مُقدمة
بدأ تاريخ الأرض والمجموعة الشمسية بسحابة سديمية Primordial Nebula من غازات وغبار كوني
نشأ بمركز السدیم دوامة كبيرة أدت لتدافع مادته نحو داخله فيما يعرف بالانكماش الجذبي Gravitational Attraction
استمر الانكماش فازداد الضغط والحرارة بجوفه فأدى لبدء تفاعلات نووية أشعلت الهيدروجين فأضاءت الشمس التي كانت خاضعة لقوتين متعادلتين هما الطاقة الحرارية من جوفها التي تزيد حجمها والانكماش الجذبي الذي يقلص حجمها فاستقرت حتى يومنا هذا
حدثت دوامات صغيرة بأطراف السديم أدت لنشوء الكواكب التسعة المحيطة بالشمس ونظرا لصغر حجم السديم لم تصل درجة حرارة جوفها لدرجة بدء التفاعلات النووية فبقيت الكواكب أجسامة باردة غير مضيئة
الأرض والكواكب القريبة من الشمس خضعت اثناء تكاثف سديمها للرياح الشمسية التي طردت الغازات المكونة للسدیم وبقيت العناصر الأكثر ثقلا وكذلك دقائق الغبار الكوني التي تجمعت فشكلت الأرض الصلبة
جاءت مرحلة النشاط البركاني الشديد التي دفعت كميات كبيرة من الغازات لجو الارض اهمها بخار الماء الذي هطل مكونا مياه البحار واصبح هواء الارض مكونا من غازات مثل كبريتيد الهيدروجين والامونيا والارغون والهيليوم والنيتروجين وغيرها،
الاكسجين لم يكن موجود فكان الجو مختزل Reducing
كانت الأشعة فوق البفسجية تصل لسطح الارض اذ لم يكن بغلاف الأرض ما يمنعها من الوصول وقد فككت او تفاعلت هذه الاشعة عالية الطاقة مع بعض اكاسيد الغازات كبخار الماء مثلا محررة الأكسجين غير أن هذا الأكسجين الحر كان يستهلك بسرعة من الغازات المختزلة، سميت هذه المرحلة مرحلة التمثيل الكيميائي chemosynthesis
قبل 3500 مليون سنة بدأت كائنات حية كالبكتيريا بالوجود على الأرض والتي لا تحتاج الأكسجين بل تاخذه من عمليات كيميائية ، غير أن اهم ماكانت تقوم به انها كانت تاخذ ثاني اكسيد الكربون من الجو لتصنع غذائها بعملية التمثيل الضوئي Photosynthesis
كانت هذه الكائنات تطلق الأكسجين الحر الذي ادي لظهور الكائنات الحية التي تحتاج الأكسجين
الأرض شهدت عمليات جيولوجية نتج عنها تكوين المعادن كالحديد والفضة والذهب والرصاص والماس والفوسفات وتكونت مصادر طاقة احفورية كبترول وغاز وفحم حجري
More than 150 people die each year in USA from floods & flash floods, more than any other natural disaster
Why do we study Meteorology?
1. Daily Weather: how we plan our days
2. Severe Weather: damage, & loss of life
3. Climate Change: quality of life, water & food supplies
Severe Weather Includes
tornadoes, hurricanes, snow storms, floods, thunderstorms…etc
Recent Weather Events
1. Hurricane Sandy: 2012, > 253 people killed in 7 countries, Cost estimated at 65.6B$, which would make it the 2nd costliest Atlantic Hurricane behind only Katrina.
2. Joplin Tornado: 2011, 158 people killed & > 1,100 injured, It was dead lies tornado in America since 1947
3.VOG:2012, Trade Wind Weaken (respiratory complaints, headache, watery eyes, severe sinus infections), sulfur dioxide SO₂ gas & sulfate SO₄ aerosol which can cause acid rain/acid particles
4.Great Plains Drought: 2012, Worst hit region is the Central Great Plains, Critical for agriculture!
Meteorology
Is the study of atm & its phenomena
– mathematical science ❤
– The term goes back to Aristotle who wrote a book about meteorology
– Meteor means “high in the air”, Weather instruments in the 6th century
Weather
The state of the atm at any given time
Weather elements: Air T & P, Humidity, Clouds, Precipitation, Visibility, & Wind
Climate
sum of all statistical weather information (Average range of “weather element” over long period of time)
description of aggregate weather conditions
Includes extreme weather event (Droughts, heat wave, & cold snaps)
Climate changes on geological time scales such as ice ages
Climate VS Weather
Climate is what you expect, & weather is what you get
Atmospheric Compositions
Evolution of the atm
1. First atm: H & He, 4.6 BY ago, swept away by solar winds, & escaping hot surface
2. Primeval Phase: mostly CO₂, N₂, H₂O, little CH₄, NH₃, SO₂, HCl
3. Μodern Phase: 78%N, 21%O, 1%Ar, <1% other gases & aerosols
After 4 BY, surface cooled, Water vapor to condense into clouds so rain, Oceans, & rivers formed
CO₂ dissolves in H₂O: rain & ocean “washed out” CO₂, cooling the planet
O₂ building up in the atmosphere: After life emerged, photosynthetic bacteria emerged
Source of atm gases was OUTGASSING release from rock through volcanic eruptions & meteorites impact
Μodern Phase Composition
78% Nitrogen N₂
21% Oxygen O₂
< 1% Argon Ar
Carbo (–dioxide CO₂, -monoxide CO)
N (-dioxide NO₂, -oxide NO), Nitrous N₂O
Sulfer oxide SO, Hydrogen H₂, Helium He
Methan CH₄, & Ammonia NH₃
Ozone O₃, & Water vapor H₂O(g)
aerosols: tiny solid & liquid particle:
– dust, & smoke
– sea salt, & biogenic particle
– pollution, & volcanic ash
Where did all the Nitrogen come from?
1. N₂ is volatile in most of its forms
2. N₂ unreactive with materials that make up the solid earth
3. N₂ stable in solar radiation environment
– Over geological time, it has built up much greater than O₂
– It is an important component of life on earth (N-Cycle)
Why is Argon Third?
1. formed by radioactive decay of potassium isotope, & Released into atm by volcanic activity
2. inert gas, nonradioactive, so gradually accumulates in atm
-Used in Neon Lights
Where does oxygen come from?
1. Primary way is photosynthesis (98%)
2. The breakup of water molecules by ultraviolet radiation (1-2%)
Ozone O₃
concentrated above surface in stratosphere (good) & in Troposphere (poor)
Protect us from UV rays (what gives us sun burns)
Ozone Hole: in the Antarctic, though one happened in Arctic
Montreal Protocol
water vapor H₂O(g)
variable over the surface of the earth (0-4% by volume)
most abundant GHG: Heats atm (Releases or absorbs energy if it changes states )
Methan CH₄
GHG
from cows, wetlands, & rice pattie
low oxygen environment
Carbon dioxide CO₂
GHG
from respiration, combustion, & evaporation
Global Climate Change
present in tiny amouont ≈ 0.0387% ≈ 387ppm (increase since 1960s)
an efficient absorber of energy emitted by the sun!
atm Provides
air we breath
protection from damaging of UV radiation
Thermal Structure
as altitude (height) increases
layer Rapidly thins (density decreases)
P decreases (Not at a constant rate)
near surface air more dense, & Decreases rapidly at first then more slowly
P decreases as altitude increases
Layers of atm VERY THIN: 99% is within 30km
Half atm is lies below 5.6km
Standard atm P = 1013.25mb = 1013.25hPa = 29.92Hg
Air is HIGHLY compressible
What happen if astronaut exposed his hand in Thermosphere?
not feel hot, not enough particles
how the current atm evolved?
1. Outgassing
2. Photosynthesis
Ionosphere [80-400]km
an electrically charged layer, Overlaps with Thermosphere, site of Aurora
No influence on daily weather
Important for long wave radio transmission that Travel in straight lines & bounce off the Ionosphere
– at night F layer reflects AM waves
– in daylight D layer absorbs AM waves
Aurora [100-400]Km
Closely correlated with solar-flares & Appear in the night sky as overlapping curtains
phenomenon that forms as energetic particles from sun & interact with Earth’s atm
Aurora boreal (northern lights)
Aurora austral (southern lights)
Geographic location is important (Earth’s magnetic poles)
produce by solar wind distorts Earth’s magnetic field into magnetosphere & These particles interact with gases to produce aurora
– solar wind stream of charged particles
– magnetosphere has teardrop shape
The End
Environmental and applied geology 