The eruption of Eyjafjallajökull?

Batch, 284 bytes

@set e=echo 
@%e%off
set s=      
set t=   
goto %1
:RED
set t= ` 
%e%   `~ ~ ~ ~ ~ ~`
:ORANGE
%e%   %t%~  ~  ~%t%
:YELLOW
%e%    %t%~   ~%t%
%e%%s%%t%~%t%
:GREEN
%e%%s%al   la 
%e%     j%s% j
%e%  jaf %s%  oku
%e% y %s%%s%  l
%e%E%s%%s%%s%l
%e%--------------------

Note: Lines 1 and 7 have one trailing space, line 3 has six and line 4 has three.

Ruby, 161

Here's my take on Iceland's famous landmark, the Eyjafjallajökull Tower.

Reasonably short but I haven't come up with a good way to golf the smoke yet.

->n{m=85-n[-3].ord>>2
%w{`~+~+~+~+~+~` `+~++~++~+` `+~+++~+` `+~+` al%3sla j%7sj jaf%9soku y%15sl E%17sl}.map{|i|(i%"").tr(?++?`*m," ").center(19)}[m,9]+[?-*19]}

Ungolfed in test program

f=->n{m=85-n[-3].ord>>2     #From ASCII code of 3rd from last letter, derive m=0 for RED up to 4 for GREEN (uppercase.)
  %w{`~+~+~+~+~+~` `+~++~++~+` `+~+++~+` `+~+` al%3sla j%7sj jaf%9soku y%15sl E%17sl}.
  map{|i|                   #For each line above decode as follows:
    (i%"").                 #Replace %Xs with X spaces, by inserting  empty strings and padding sprintf style. 
    tr(?++?`*m," ").        #Replace + with space. If not red, replace ` with space.
    center(19)}[m,9]+       #Centre output to 19 characters per line. Start printing at line m and go on to the end (never more than 9 lines.)
  [?-*19]                   #Add a row of --- at the bottom.
}

puts f[gets.chomp]