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Ozonlag

Ozonlag

Ozonlaget er en betegnelse for det lag af atmosfæren, der befinder sig mellem 10..50 km over jordens overflade, hvor 90% af gasarten ozon er. I dette lag opfanges den skadelige UVC stråling, samt meget af UVB og lidt af UVA. Dette sker i en proces, hvor strålingen spalter ozon til iltmolekyler og -atomer og samtidig spalter iltatomer til molekyler der reagerer og danner ozon. I de senere år er man begyndt at tale om huller i ozonlaget, der angiveligt skulle være foresaget af øget forurening og udledning af CFC-gasser. Disse huller betyder at større mængder stråling kan trænge ned til jorden, hvilket er skadeligt for livet der. Indtil videre har man dog kun observeret et sådan hul over Antarktis. Der har været en tendens til at forveksle ozonlagsproblematikken og drivhuseffekten. Dette er forkert, da de to problemer er vidt forskellige, også selvom de måske begge udspringer af øget forurening.

Eksterne henvisninger


- [http://www.ing.dk/apps/pbcs.dll/article?AID=/20030814/RUMFART/108150031 14.08.2003, Ing.dk: Ozonlaget får det bedre]
- [http://www.cnn.com/2005/TECH/science/08/31/ozone.layer.reut/index.html August 31, 2005, CNN: Study: Ozone layer has stopped shrinking]
- [http://www.sciencedaily.com/releases/2005/08/050831074639.htm 2005-08-31, Science Daily: Changes In Ozone Layer Offer Hope For Improvement, Says Team Of Scientists] Citat: "...Analysis of several different satellite records and surface monitoring instruments indicates that the ozone layer is no longer declining, according to a study by scientists working with the Center for Integrating Statistical and Environmental Science (CISES) at the University of Chicago..." Kategori:Økologi Kategori:Meteorologi ja:オゾン層 ms:Lapisan ozon

Ozon

Ozon er en luftart (O3) i stratosfæren, der beskytter mod ultraviolet stråling. Industrielt bruges ozon som en kraftig oxidator. Ozon er kemisk ustabilt, og tilstedeværelsen af selv forsvindende mængder af "fremmedstoffer" gør det yderst eksplosionsfarligt. Af den grund bruges ozon ikke som iltningsmiddel i raketters motorsystemer, til trods for at ozon er mere kompakt end en tilsvarende mængde "normal", molekylær ilt (O2). Ozon kan dannes ved en spontan reaktion mellem svovlilte (SO2) og forskellige kvælstofilter (NOx). Da disse luftarter oftest findes, hvor man har røg fra kraftværker, fabriksskorstene m.m. i blanding med udstødningsgas fra biler, vil der dannes ozon i tæt trafikerede områder af vore byer. Ozonens ustabilitet fører til, at der dannes frie iltatomer (O), som er yderst aggressive over for levende væv. Det kan f.eks. ses af de talrige ozonskader på bytræer og -buske (skaden ligner "blancherede" pletter). På den måde kan ozonskader bruges som indikator for, at der er svovlilte og kvælstofilte i luften. Ozons ætsende virkning på levende væv har tidligere været udnyttet lægeligt ved, at man lagde tuberkulosesanatorier i tætte nåleskove. Der dannes nemlig en smule ozon, hvor der vokser nåletræer, og ved indånding fik man dræbt tuberkulosebakterierne dybt nede i patienternes lunger. ---- Kilder/henvisninger
- Lexopen

Se også


- Jordens atmosfære ja:オゾン ko:오존 ms:Ozon

UVB

Ultraviolet lys (også UV lys, ultraviolet stråling eller UV stråling) er elektromagnetisk stråling som har kortere bølgelængde end synligt lys og længere end blød røntgenstråling. Ultraviolet lys dækker således bølgelængdeintervallet 380 nm - 10 nm. UV lys indvirker på mange biologiske og kemiske processer.

Ultraviolet lys bølgelængder

I følge mange kilder (NASA, FDA og andre) bliver ultraviolet lys opdelt i følgende bølgelængdeintervaller:
- UVA også kaldet sort lys 400 nm - 320 nm (bliver ikke absorberet af ozonlaget og ozon).
- UVB 320 nm - 290 nm (det meste bliver absorberet af ozonlaget).
- UVC 290 nm - 100 nm (Fuldstændigt absorberet af ozonlaget). Herudover opdeles UV-lys i:
- nær UV, NUV (380–200 nm).
- ekstrem UV, EUV eller vakuum UV (200–10 nm).

Anvendelser/virkninger

UVA

Meget af det papir og de tekstiler vi anvender i dag, bliver tilsat stoffer, som er fluorescerende i UVA lys (UVA resulterer i udsendelse af blåligt lys). Den oprindelige grund til dette var at gøre hvide stoffer endnu hvidere. UVA lys bliver anvendt af filatelister, da frimærker i en bestemt tidsperiode blev trykt både på fluorescerende og på ikke-fluorescerende papir. Man kan klart skelne mellem de to papirtyper ved at belyse det med en (f.eks. batteridrevet) UVA-lampe. Nogle pengesedler har sikkerhedsmønstre, som træder frem ved UVA belysning. Nogle dyr, som f.eks. bier, kan se UV lys. Formodentlig hjælper dette dyrene til at finde blomster, og for flagermus ved man, at de anvender UV-lys til at finde blomster om natten. UVA ødelægger langsomt mange typer af farvepigmenter; derfor har nogle forretninger sat (specielt) gult folie i udstillingsruden for at dæmpe UVA lyset.

UVA og UVB

Det er kombinationen af UVA og (lidt) UVB lys, som stimulerer vores hud til at gøre os brune (UVA lys alene er ikke nok). Huden danner det brune pigment melanin (undtagen hos albinoer). For hvide mennesker tager det fra nogle dage til uger før huden har dannet tilstrækkeligt med beskyttende melanin, derfor skal man være varsom med solbadning eller udendørs arbejde ved solskin i starten af året. Når vores hud indeholder melanin og huden får UVA+B lys dannes gavnlige D3-vitaminer. En anden virkning som UVB lys har er, at det ødelæggger kollagenet i vores hud. Forfatteren ved ikke om melaninet beskytter mod denne virkning. Ved visse hudforandringer eller hudsygdomme kan solbadning have en gavnlig virkning. En læge vil ordinere en sådan behandling i de aktuelle tilfælde. ([http://www.sundhedsguiden.dk/illness.aspx?name=Pigmentforstyrrelser+&categoryId=559&article=1384 kilde sundhedsguiden.dk]). Da større mængder af UVA+B lys er skadeligt, anvendes solcreme til at absorbere disse. "Almindeligt glas" beskytter mod UVA og UVB, da det absorberer dette lys. Krystalglas (næsten kun kvarts SiO2) derimod, tillader passage af UVA og UVB. Da halogenpærer normalt består af tyndt krystalglas, udsender halogenpærer UVA og muligvis UVB lys. Derfor er er det i dag påkrævet at halogenlamper har UVA og UVB absorberende "almindeligt glas" foran sig (minimum 2 mm) for at beskytte os.

UVB og UVC

UVB og UVC er kemisk stærkt aktive stråler, som ødelægger de fleste organiske molekyler (incl. DNA). UVB og UVC lamper anvendes derfor til at sterilisere biologisk udstyr eller hospitalsudstyr, så man får slået mikroberne på udstyret ihjel.

Kilder/referencer


- [http://www.epa.gov/sunwise/uvradiation.html EPA SunWise UV Radiation]
- [http://www.physlink.com/Education/AskExperts/ae300.cfm Question: What is the wavelength of UVa, UVb, and UVc light measured in nanometers, and frequency (in Hz)?]

Se også


- Sollys
- Solbruning
- Lysstofrør
- Ultraviolet lampe, Ultraviolet lysstofrør
- Ozonlag Kategori:Fysik ja:紫外線 ms:Ultraungu simple:Ultraviolet

Ilt

Ilt eller oxygen er et grundstof, der ved atmosfærisk tryk har gasform. Det optræder som regel som almindelige iltmolekyler med to iltatomer (O2), men også, i mindre omfang, som ozon med tre iltatomer (O3). ozon Ilt er nødvendigt for respirationen og dermed for den aërobe udnyttelse af kemisk energi, bundet i organiske forbindelser. Det er væsentligt at huske på, at selv planter har respiration (og altså et iltforbrug), selv om de oftest har en større frisættelse af ilt gennem fotosyntesen. Under særligt lysfattige forhold (for eksempel om natten) eller i kraftig varme kan planters forbrug af ilt overstige deres produktion af ilt. Ozonlaget i stratosfæren er afgørende vigtigt for atmosfærens filtrering af ultraviolet stråling og på den måde gavnligt for alle levende væsner på kloden. Derimod er ozon, når det optræder i jordhøjde, et forureningsproblem, pga. ozons giftige, ætsende natur. Ilt står listet som nr. 8 i det periodiske system. Jordens atmosfære indeholder 20,9% ilt. Det danske navn ilt er dannet af H. C. Ørsted af ordet ild (sammenlign brint). Tidligere blev det kaldt surstof, der ligesom tysk Sauerstoff er en direkte oversættelse af det græsk-latinske oxygenium.

Se også


- Joseph Priestley Kategori:Grundstoffer als:Sauerstoff ja:酸素 ko:산소 ms:Oksigen simple:Oxygen th:ออกซิเจน

Antarktis

Antarktis er et kontinent og kaldes også for Sydpolsegnene, da Antarktis midte er den geografiske sydpol. Ligesom Arktis har Antarktis lave temperaturer året rundt især omkring juni måned, hvor der er mørkt døgnet rundt, på grund af vinteren. Om sommeren omkring december måned er der lyst døgnet rundt. Antarktis blev opdaget i slutningen af januar 1820; Der er diskussion om hvem der var først: Englænderen Edward Bransfield, russeren Fabian von Bellingshausen eller amerikaneren Nathaniel Palmer. Nathaniel Palmer

Dyre- og planteliv

Af større dyr er der:
- Pingvin
- Sæl
- Der er mange dyr i havet omkring Antarktis. Af smådyr eller planter er der:
- Krill - krill er mange hvalers primære føde
- Alge - for eksempel på undersiden af havisen - mange smådyr (eksempelvis lyskrebs) græsser alger herfra
- Tang
- Dybhavsreje

Se også


- antarktis, arktis, breddekreds, datolinjen, jævndøgn, lyse nætter, længdekreds, meridian, nordpolen, polarkreds, solhverv, Skt Hans, sydpolen, vendekreds, Ækvator

Eksterne henvisninger


- [http://www.aad.gov.au/asset/webcams/ Australian Antarctic Division - Station Webcams and weather] f.eks. [http://www.aad.gov.au/asset/webcams/davis/ davis], [http://www.aad.gov.au/asset/webcams/mawson/ mawson]
- [http://www.ecoscope.com/iceberg/index.htm Iceberg images from Antarctica] (billeder af isbjerge)
- [http://www.ge.ucl.ac.uk/%7Eawayne/polar/geography.html Planetary Visions: The Geography of the Poles] Se 2D og 3D videofilm.
- [http://unisci.com/stories/20013/0702012.htm 02-Jul-2001, UniSci: High Level Of Air-Purifying Agent Found At South Pole] Kategori:Geografi Kategori:Verdensdele Kategori:Antarktis ja:南極大陸 ko:남극 simple:Antarctica th:ทวีปแอนตาร์กติกา

Kategori:Økologi

Kategori:Akademiske discipliner Kategori:Natur Kategori:Biologi ja:Category:生態学 ko:분류:생태학

German 1st Fallschirmjäger Division

The German 1st Parachute Division was a German military parachute-landing Division that fought during World War II. A division of paratroopers was termed a Fallschirmjäger Division. It was originally raised as the 7th Flieger, or Air Division, before being renamed and reorganized as the 1st Fallschirmjäger Division in 1943.

History

In October 1938, the decision was made to raise the 7th Flieger (Air) Division. This was to be an élite paratroop formation intended for vertical envelopment operations against enemy defenses. The commander chosen to lead the 7th Flieger Division was Major-General Kurt Student. Organizationally, a Fallschirmjäger Division was intended to be organized along the lines of a German Infantry Division, with three parachute rifle regiments, an artillery regiment, and divisional support units. However the Division was not brought up to full strength before 1941. Nevertheless, elements of the Division played significant roles during the Wehrmacht operations in 1940. At the start of the World War II, the Division consisted of the 1st and 2nd Parachute Regiments. The 7th Air Division performed its first war-time parachute drops in September 1939, when two battalions were air-dropped to capture Polish airfields. The goal of the mission was to prevent senior officers of the Polish army from escaping the country before they could be captured. One of the battalions saw its first combat during this operation. In April 1940 the 1st battalion of the 1st Regiment was used to capture key airfields in Denmark and Norway during Operation Weserübung. These missions were successful, and the airfields proved key staging bases for the Luftwaffe to transport troops to Norway as well as fighter aircraft operating out of Denmark. A later, company-sized airdrop operation at Dombas proved a failure, however, as the unit quickly ran out of supplies and was taken prisoner by the Norwegian army. By May 14th, the 1st Battalion, 1st Regiment was concentrated and parachute dropped at Narvik, Norway to reinforce the German mountain troops in the battle for that key port. The battle for Norway came to an end on June 8th. June 8, 1940]] For Operation Gelb, the German plan for the invasion of Belgium, France, and the Netherlands in May 1940 called for the use of the 7th Air division to aid in the advance through the capture of key bridges and the fortress of Eben Emael. For the Belgian operations, an assault battalion was formed. The four companies of this battalion were assigned the following objectives: :
- Capture the bridge at Schachter. :
- Capture the bridge at Veldwezelt. :
- Capture the bridge at Vroenhoeven. :
- Take the fortress at Eben Emael. Of these, three of the missions were entirely succeessful; the exception being the bridge at Schachter, which was blown up by the Belgian defenders. The attack upon the Netherlands included the majority of the 7th Flieger Division in cooperation with 22nd Luftlande-Infanterie Division. The primary goal of the airlandings was to capture the Dutch seat of residence, The Hague; a secondary goal was to secure critical bridges in order to allow a German mechanised advance through the fortified positions of the Dutch defenses. These bridges were those at Dordrecht, Moerdijk, and the Nieuwe Maas. The parachute drops were also used to capture the Waalhoven airfield near Rotterdam, where additional forces would be air-landed. Initially the attacks were successful, but hard fought and some units took heavy casualties. The attack on The Hague was a failure: many paratroopers were captured and 1200 prisoners of both divisions were transported to England. All bridges were succesfully held against Dutch counterattacks however. The airlandings occupied Dutch troops at a time when they were needed to slow the German land advance. Shortly after the surrender of Rotterdam, General Student became wounded by friendly fire, being accidentily shot in the head by soldiers of Leibstandarte Adolf Hitler. While he recovered, the command of the division was temporarily assumed by General Putzier. The Dutch surrendered on May 14th after Rotterdam was heavily bombed. The invasion of France proceeded without further operations by the Division. With the signature of the armistice on June 22nd, the German victory over the French army was complete. The summer months would be used in preparation for Operation Seelöwe, the planned invasion of England. Airborne troops were to play a significant role during the initial landings, as they were assigned the task of capturing Lympne airfield on Romney Marsh. However the 7th Air Division and the German 22nd Air Landing Division had taken losses during the preceding campaign, and were now understrength. The invasion plans were shelved on October 12th, and the Division had time to train new recruits. At the start of 1941, the OKW decided to create the German XI Air Corps, which would include the 7th Air Division. This Corps would be under the command of General Student, and General Süssmann would become the new commander of the 7th Air Division. In April of 1941, the German army invaded Yugoslavia and Greece. The German army advanced rapidly, and had reached Thebes Greece by April 26th. That same night, the Division's 2nd Regiment was dropped at Corinth with the objective of capturing the bridge across the canal that cuts the Isthmus of Corinth. Initially the attack by the lead elements succeeded, but the British counter-attacked and in the process the bridge was destroyed. Nevertheless the force held a bridgehead across the Isthmus, and the Germans proceeded to capture the Peloponnesos. Peloponnesos]] With the surviving Allied forces withdrawn to Crete, the Germans decided upon an air-landing operation to capture island. Operation Merkur (Mercury) would use the 7th Air Division to capture airfields on Crete, then German mountain troops would be flown in as reinforcements. The 7th Air Division began parachuting onto the island on April 20th, landing as follows: :
- Herakleion - 1st Regiment; 1st battalion of 2nd Regiment :
- Retimo - 2nd and 3rd battalions of 2nd Regiment :
- Canea and Suda Bay - 3rd Regiment During the approach, General Süssmann was killed and General Sturm assumed command. The Allied forces on the island put up a stubborn defense and the troops of the 7th Air Division took heavy losses, with over 6,700 killed and wounded out of 22,000 men. With the aid of the follow-on reinforcements, however, the Allies were forced to evacuate the island by 29th. In August 1941 the 7th Air returned to Germany. The invasion of the Soviet Union was now underway, but the Division would play no role during the first summer. The losses suffered in the Crete landings were made good with newly trained recruits, and by September 1941 the Division was back up to strength. On September 24th the Division received orders to move to the Leningrad front in Russia. As in past campaigns, the élite 7th Air Divison was again frequently to be used in Company and Battalion-strength units, patching up battle lines whenever the German defenders started to waver against Soviet attacks. This experience led the Paratroopers to name themselves "The Fuehrer's Firemen". Beginning September 29, the 1st and 3rd Regiments of the 7th Air Division joined the defense of the salient along the Neva River. The battle continued into the first Russian Winter, with units taking heavy losses during the conflict. Finally in mid-December the Division was relieved and returned to Germany. Meanwhile in November the 2nd Regiment was deployed to the southern sector to participate in the defense against the Russian winter offensive. They remained on the front throughout the winter, suffering more from the difficult climactic conditions than from enemy actions. By March 1942 the 2nd Regiment was posted to the Volkhov front, to the southeast of Leningrad, defending against the fierce and continuing Russian attacks. When the 2nd Regiment was returned to Germany in June, 1942, it was detached from the 7th Air Division and would form the nucleus of the German 2nd Parachute Division. The 7th Air Division was now recovering in Normandy, France. To replace the 2nd Regiment, the 4th Parachute Regiment was raised and merged into the Division. Later in the year, plans were made to use the Division in the German summer offensive in Russia. However the operation was cancelled, and the Division was deployed in the Rzhev sector near Smolensk in October. Much of the winter months were spent patrolling and performing limited attacks along the front. The battle of Stalingrad was underway, and Soviet attentions were focused on the southern part of the front. This situation changed in March 1943 when the Soviet army assaulted the Divisional front. This attack was beaten back with heavy Russian losses. By May the Division had returned to Germany, after being used to form the 1st Fallschirmjäger, or Parachute Division. The formation was then moved to Avignon, France for rest and refitting. Their brief respite came to an end in July, however, when the Allied forces landed in Sicily on July 10th. Most of the Division was moved to Catania airfield starting July 12th to participate in the defense of the island. Again the division was used in fire-brigade fashion, stiffening the defenses wherever they started to waiver. As the decision was made to withdraw, the 1st Parachute Division was employed as the rearguard defenses as the evacuation proceeded. They were the last German unit to leave the island on August 17th. For the remainder of the war the Division would fight during the Italian Campaign. They were employed piecemeal to ward against the possibility of sea-landings from Salerno to Taranto, and fought another withdrawing action up the Adriatic coast of Italy against the advancing Allies. By Winter the Division was concentrated in the defense of the Gustav Line south of Rome, defending against the advance of the British Eighth Army under General Montgomery. On January 1944, the US IV Corps made an amphibious landing at Anzio, about 50 kilometers south of Rome. Unfortunately for the Allies the landing quickly bogged down and failed to advance. To support the landing, the Allied armies in the south needed to break through the German defenses of the Gustav Line. In February 1944, the 1st Parachute Division was pulled out of the line and shifted to the defense of Monte Cassino. This dominant position laid astride the road to Rome, and must be taken by the Allies if they were to advance. The Division put up a ferocious defense of the site, which even carpet bombing of the Monte Cassino Abbey on March 15 failed to dislodge. The battle was finally broken off on March 22nd. :"No other troops in the world but German paratroops could have stood up to such an ordeal and then gone on fighting with such ferocity" — Field Marshall Alexander. During the fight the Division took many losses, including the 3rd battalion of 1st Regiment. However the Allies would not resume their attack until May 11th, and the Division had time to make good its losses. When the attack resumed with the third battle of Cassino, the German defenses held out until May 17th before the line became flanked along the coast. The 1st Parachute Division joined a general German withdrawal to the north of Rome. The paratroops performed delaying actions against the Allies until they reached defensive positions in the Apennine Mountains to the south of Bologna. They now formed part of the German I Parachute Corps, along with the German 4th Parachute Division. The Italian front remained static throughout the winter months, with only sporadic patrols and raiding actions. By January 1945, the German I Parachute Corps was deployed to the Adriatic coast behind the Senio Rivier. The Allied advance resumed on April 8th, and the 1st Parachute Division was forced into a steady withdrawal toward the Po River by the British Eighth Army. By April 25th the Division had completed the river crossing. They immediately set off on a final march toward the Alpine Mountains. Finally the German surrender in Italy came on May 2 1945, and included the men of the 1st Parachute Division. The unconditional surrender of Germany followed a week later.

Commanders

Organization

September 1939
- 7th Air Division
  - 1st Parachute Rifle Regiment
    - 3 Battalions
  - 2nd Parachute Rifle Regiment
    - 2 battalions May 1941
- 7th Air Division
  - 1st Parachute Rifle Regiment
  - 2nd Parachute Rifle Regiment
  - 3rd Parachute Rifle Regiment
  - 7th Artillery Battalion
  - 7th Anti-tank Battalion
  - 7th Flak Battalion
  - Machine-gun Battalion
  - Pioneer Battalion
  - Other divisional units April 1943
- 1st Parachute Division
  - 1st Parachute Rifle Regiment
  - 3rd Parachute Rifle Regiment
  - 4th Parachute Rifle Regiment
  - 1st Parachute Artillery Regiment
    - 2 battalions
  - 1st Parachute Anti-Tank Battalion
  - 1st Parachute Engineer Battalion
  - 1st Parachute Machine-gun Battalion
  - Other divisional units

See also


- Airborne forces

References


- Lucas, James. Storming Eagles: German Airborne Forces in World War Two. Arms and Armour Press, 1988.

External link


- [http://www.eagle19.freeserve.co.uk/index.html Fallschirmjäger] - a site dedicated to this unit. Category:German airborne units Category:German parachute divisions Category:German World War II divisions

Hotel Genoa ebay Dorota Rabczewska Dorota Rabczewska Parkiet










































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