Inspired by Craggles' dragonfire I spent some time in the lab last night making fireballs then the power went out and I lost the last half of it. This is a redo of it all. Start with a document 1000 x 1000, rgb.
1. Filter - render - clouds. Duplicate the layer. Then run Difference clouds at least 8 times.
2. New layer, big airbrush with white (I used a 300 pixel modified up to 600), make a dot in the middle and set the layer to soft light.
3. New layer, repeat step 2 but leave the layer at normal but drop the opacity to 75%.
4. Use a black airbrush and brush around the edges to remove any light colors there...keep the light colors around the middle but not necessarily circular.
5. New layer. Hold down ctrl + shift + alt + E...this merges all visible layers into the new empty layer. Rename this layer to "Fire".
6. Grab the Elliptical Marquee tool. Draw out a circular selection by holding down alt + shift and clicking and dragging outward. Select - feather = 50.
7. Filter - distort - spherize = 100% and normal. Repeat then deselect.
8. Duplicate this layer and rename to "Round".
9. Filter - render - lighting effects = use the settings in the screenshot.
10. New layer and fill it with black. Move this layer down under the Fire layer. Click on the Fire layer and hide the Round layer.
11. Select - all. Edit - copy. Click on the Channels tab and at the bottom click on "Create new channel" then Edit - paste and deselect (ctrl+D).
12. Ctrl + click on this layer in the Channels tab then click back on the Layers tab. Click on the Fire layer and at the bottom click on "Add layer mask".
13. Click on the Round layer. Hover your pointer over the mask on the Fire layer (its on the right side) then ctrl + click and then on the Round layer click on "Add layer mask".
14. Click on the little thumbnail on the left side (the one on the right side is the mask) because we want to play with the layer itself and not the mask now. Hide this layer and click on the Fire layer.
15. Now we need some color on this thing so Image - adjustments - gradient map. Make a gradient that goes from dark red to orange to yellow to light yellow. Play around with the colors and the sliders. I put my light yellow on the far right, yellow at 95%, orange at 70% and dark red at 35%. I attached a screenshot of my gradient.
16. Click back on the Round layer and apply the same gradient map but set the layer's blend mode to lighten.
17. Let's work on the ball so use the Elliptical Marquee tool and drag out another circle. Click on the layer with the black and white difference clouds (it should be named background copy). Edit - copy. Click on the Round layer then Edit - paste.
18. Ctrl + click on this layer and do the spherize twice then deselect.
19. Apply the same gradient map - one caveat, though. If you have a lot of black or white then you will have to play with the sliders to get the look we need here something that is mostly red with some yellow areas around the edge. Mostly red and orange overall.
20. Rename this layer to "Ball".
21. Set the layer's opacity at 50% and the blend mode to Pin Light (this lets the flames look like they're coming off the ball rather than be behind the ball). It doesn't always work out perfectly so you may have to repeat steps 17 - 20 to get something that really shows the flames coming off of the ball. The flames will look better if there are more yellows around the edges. You should see the edge of the ball where it is darker.
22. Duplicate this layer. Set the blend to Lighten and the opacity at 100%.
23. Add a Layer style of Inner Glow. Keep the default color but change it from edge to center. Play around with the size until the inside of the ball glows the way you want it.
24. Ctrl + click on this layer. Select - modify - contract = 5. Select - feather = 5. Select - inverse. Filter blur - Gaussian blur = 25. Deselect.
25. Repeat step 24 on the lower Ball layer.
26. On a new layer make any adjustments that you want. I took some red and brushed in an arc on the underside to enhance the 3d feel, used some orange just above this, and some yellow on the top. I also duplicated the Round layer.
27. New layer. Ctrl + shift + alt + E. Hide all layers except this layer.
28. Edit - transform - perspective. Hold down the shift key and click on the lower left corner box thingy and drag it inward. This will make the fireball smaller and keep the tail larger. Those of you who have the Warp tool can do quite a bit more than I can at this point.
29. Grab the Rectangular Marquee tool and drag out a rectangle that encompasses the tail but not the ball. Select - feather = 50.
30. Edit - transform - scale - grab the middle box thingy and drag it upwards until you get a nice long tail.
31. Filter - distort - wave = leave the numbers as is except where it says "Wavelength" change the number in the box for Max to something large like 500 or more (I went with 800). This will put some wiggle in our tail. You can also use shear. Deselect when done.
32. Since this fireball has a direction we will have to lighten the leading edge with some yellow and white airbrushing and darken the trailing edge with some orange and red.
33. Play around with motion blur, radial blur, move the flames around etc. Have fun with it.