BlastSim

(iOS version is no longer available for download)

Fireball (Purple): 
The fireball is the hot ball of gas created when a nuclear explosion heats the bomb itself, and the immediate surrounding environment, to very high temperatures.
 
20 psi Air blast (Red):
Heavily built concrete buildings are severely damaged or demolished. Fatalities approach 100%.
 
Radiation (Green):
Acute Radiation Sickness, about 400-600 REMS; Mortality rises steeply in this dose range, from around 50% at 450 rems to 90% at 600 (unless heroic medical intervention takes place). Hematopoietic tissues remain the major affected organ system. Initial symptoms appear in 0.5-2 hours, and last up to 2 days. The latency period remains 7-14 days. The symptoms listed for 200-400 rems increase in prevalence and severity, reaching 100% occurrence at 600 rems. When death occurs, it is usually 2-12 weeks after exposure and results from infection and hemorrhage. Recovery takes several months to a year, blood cell counts may take even longer to return to normal. Female sterility becomes probable.

3 psi Air blast (Brown):
Residential structures collapse. Serious injuries are common, fatalities may occur.

Thermal blast (Orange): 
Third-degree burns. cause tissue death all the way through the skin, including the stem cells required to regenerate skin tissue. The only way a 3rd degree burn can heal is by skin regrowth from the edges, a slow process that usually results in scarring, unless skin grafts are used. Before healing 3rd degree burns present serious risk of infection, and can cause serious fluid loss. A 3rd degree burn over 25% of the body (or more) will typically precipitate shock in minutes, which itself requires prompt medical attention.
 
Read more about equation used here:
 
http://nuclearweaponarchive.org/Nwfaq/Nfaq5.html