33. A surface burst Tesu_l-ts in the creation of t-arge and healXr radioactive particles which wifr far-1 dovn ,rithin ;i;;;;"'i"orrna ground zero, other, lighter and smarrer particres. however, wifl fo110w the fireb;11 and c10ud r.,rirr." .,rp,drift with the winds and then iqU.Ao*rr-ln u. piurne_fif." area in the generaf direction of persistine winds. I,lrrir-e these pirti"r"" are sma"ller than those closer to- ground zero, thev wiff on " ";;;; """i""5-"i*r be visible as dust vhenever fa110ut is sufficient to. represent a significant innaediate hazard. This falrout wilr (/i11 start coming dor,m withln fess irr.i'.,'-i"i"' and keep fauing for about a day or tvo delending on the distance froo. g"".-a "."o. The smallest particles, finally, r'ri1' be ejected into the stratospheie - .t-i"."t for a weaFon of large yiefd - and remain there for months or years, before leturning to the ground again. An airl5:.^:l-:n: :th:: 13"d, i.e. a burst *r.."" irr"-rirebat_t if *"ii .i""."tr.e sround, rr-r cause essentiarly arl r_es idu€J- radiation particles to ascend vith the firebarl and mushroom cloud' Eventually they vi.l "p."ia o,rt and return to the ground as dilute',rorld-wide faflout. 3l+. There are a. nurberthe most important ;r;":L'ff:";:."':::i#i":i'"ff:iil.::i '11"fi::I il i:'".;:k" wind' or if the winds are blowing i" aiir!""il iirections "t -ai ii""""i"alt itude s , the fallout area wilf have a very complicated shape vith possible ,,hot snots,,.Al 35 /392 Englistt Annex Page 1?0 Fig. A:5 Fallout Patterns The upper part of the figure shows an idealized set of dose-rate contours' Numbers are dose-rates ,'r, iaaTtt at one hour after the explosion' and the size of the contours corresfonds to a 10 Mt,- 56-percent fission surface burs! and a 50 kro/h .ff""iliri wind speed. The lower part is a hy-pothetical Dicture of ho\^r the ".t t.ilot'l patt;rn might look in reality' Note the change in the overall direction of the pattern' (Froi: Effects of Nuclear Weapons' Washington 1977')^/ 35 /392 English :lnn ex iaae .L / _L
**Analysis**
The text appears to be discussing the effects of a nuclear explosion on the environment, specifically the distribution of radioactive particles in the air and on the ground. It describes the movement of particles in the atmosphere and their potential impact on the surrounding area. The text also mentions the potential for long-term effects on the environment and human health.

**Category**
Science and technology, Health