Imirasire Y' Izuba
Imirasire y'izuba ni igice cy'imirasire ya electromagnetiki itangwa n'izuba, cyane cyane urumuri rutagaragara, rugaragara, n'umucyo ultraviolet . Ku isi, urumuri rw'izuba runyanyagiye kandi rukayungururwa mu kirere cy'isi, kandi bigaragara nk'izuba ryo ku manywa iyo izuba riri hejuru y'izuba . Iyo imirasire y'izuba itaziguye idahagaritswe n'ibicu, iba ifite nk'izuba, ikomatanya ry'umucyo mwinshi n'ubushyuhe bukabije . Iyo uhagaritswe n'ibicu cyangwa ukagaragaza ibindi bintu, urumuri rw'izuba rurakwirakwira . Inkomoko zigereranya impuzandengo yisi yose iri hagati ya watt 164 na 340 watt  kuri metero kare kumunsi wamasaha 24;  mibare igereranywa na NASA ko igera kuri kimwe cya kane cy'isi yose igereranya imirasire y'izuba .

Imirasire y'izuba ifata hafi 8.3 iminota yo kugera Isi uhereye hejuru yizuba.  Foton itangirira hagati yizuba no guhindura icyerekezo igihe cyose ihuye nikintu cyashizwemo byatwara hagati yimyaka 10,000 na 170.000 kugirango igere hejur.

Sunlight is a key factor in photosynthesis, the process used by plants and other autotrophic organisms to convert light energy, normally from the Sun, into chemical energy that can be used to synthesize carbohydrates and to fuel the organisms' activities.

Uko Ikpmwa

Abashakashatsi barashobora gupima ubukana bw'urumuri rw'izuba bakoresheje icyuma cyerekana izuba, pyranometero, cyangwa pyrheliometero . Kugirango ubare urumuri rw'izuba rugera ku butaka, byombi bigomba kwitabwaho ku buryo butandukanye bwo kuzenguruka isi ya elliptike y'isi ndetse no kwiyongera kw'ikirere cy'isi . Imirasire y'izuba idasanzwe ( E ext ), yakosowe kuri orbit ya elliptike ukoresheje umubare wumunsi wumwaka (dn), ihabwa ikigereranyo cyiza na 

"aho dn = 1 ku ya 1 Mutarama; dn = 32 ku ya 1 Gashyantare; dn = 59 ku ya 1 Werurwe (usibye imyaka isimbuka, aho dn = 60), nibindi Muri iyi formula dn - 3 irakoreshwa, kubera ko mugihe cya none isi ya perihelion yisi, inzira yegereye izuba bityo rero, E ntarengwa ibaho hafi ya 3 Mutarama buri mwaka. Agaciro ka 0.033412 kagenwe uzi ko ikigereranyo kiri hagati ya perihelion (0.98328989 AU) kwaduka hamwe na aphelion (1.01671033 AU) kwaduka igomba kuba hafi 0.935338."

Imirasire y'izuba ihoraho ( E sc ), ingana na 128 × 10 3 lux . Kumurika bisanzwe ( E dn ), byakosowe kubera ingaruka ziterwa nikirere bitangwa na:

aho c ni ukuzimangana kwikirere na m nikigereranyo cyiza cya optique. Kurimbuka kwikirere kuzana umubare wa lux kugeza kuri 100 000 lux.

Ingano yingufu zose zakiriwe kurwego rwubutaka kuva izuba kuri zenith biterwa nintera igana izuba bityo mugihe cyumwaka. Ni hejuru ya 3,3% ugereranije no muri Mutarama na 3,3% munsi ya Nyakanga (reba hano hepfo). Niba imirasire y'izuba idasanzwe ku isi ari watt 1367 kuri metero kare (agaciro iyo intera y'isi - izuba ni 1 yubumenyi bw'ikirere ), noneho urumuri rw'izuba rutaziguye ku isi iyo izuba rigeze kuri zenith ni 1050 W / m 2, ariko Uwiteka umubare wose (utaziguye kandi utaziguye uva mu kirere) gukubita hasi ni 1120 W / m 2 .  Ku bijyanye n’ingufu, urumuri rwizuba hejuru yisi ni hafi ya 52 kugeza 55% infragre (hejuru ya 700 nm ), 42 kugeza 43% bigaragara (400 kugeza 700) nm), na ultraviolet 3 kugeza kuri 5 ku ijana (munsi ya 400 nm).  Hejuru yikirere, urumuri rwizuba rugera kuri 30% cyane, rufite ultraviolet (UV) hafi 8%,  hamwe na UV nyinshi ziyongereye zigizwe na biologiya yangiza ibinyabuzima bigufi byangiza ultraviolet. 

  has a luminous efficacy of about 93 lumens per watt of radiant flux. This is higher than the efficacy (of source) of artificial lighting other than LEDs, which means using sunlight for illumination heats up a room less than fluorescent or incandescent lighting. Multiplying the figure of 1050 watts per square meter by 93 lumens per watt indicates that bright sunlight provides an illuminance of approximately 98 000 lux (lumens per square meter) on a perpendicular surface at sea level. The illumination of a horizontal surface will be considerably less than this if the Sun is not very high in the sky. Averaged over a day, the highest amount of sunlight on a horizontal surface occurs in January at the South Pole (see insolation).

Kugabanya imishwarara ya 1050 W / m 2 ukurikije ubunini bwa disiki yizuba muri steradians itanga impuzandengo ya 15.4 MW kuri metero kare kuri steradian. (Nyamara, imirasire iri hagati ya disiki yizuba irarenze hejuru yikigereranyo hejuru ya disiki yose kubera umwijima . ) Kugwiza ibi by π bitanga urugero rwo hejuru kuri irradiance ishobora kwibanda kumurongo ukoresheje indorerwamo: 48.5 MW / m 2 . .