www.optidigit.com/stevens/cloudtut.html

气死我了 我刚才翻译了 发送的时候居然出现找不到服务器 气气气气！！！

Painting clouds 画云朵
i used Photoshop, but any paint program should work. (Left, cropped from a larger image.)
我用PS，但是任何其他的软件也可以。（左图是从一张大的图上截下来的）

I start with a ramp like the one on the right; be careful not to use full saturation here. Up to your preference, if you want to make the background a little more purple.

我从一个在傍晚时候的云的斜面开始；小心这里不要用全部的饱和度。根据你的需要，如果你想把背景弄得更紫一点。


Start painting with max saturation and max value a 'peachy' color on a large default brush (sharp edge, pressure-sensitive opacity). Quickly block in the rough shapes where light would fall on your cloud.
开始用混合的饱和度并混合一个“桃红色的”的颜色在一只定义好的大号笔刷上（宽大的边缘，一个根据压力改变饱和度的）。快速的在光线能够到达的云的地方用光滑的笔触画出。


Take special care here (and any time you're painting something in nature) to not be too predictable, symmetrical or regular.
在这个地方特别注意（包括任何时间你画自然界的东西）不要太死板，对称或规则。
Go down in brush size and do some more detailed strokes.
减小笔刷的大小进行细节的刻画。

The shadow color is added, a purple so dull it's almost gray. Then add the darker orange/red color wherever the peach meets the shadow. Also, normally, clouds will be brighter at the top so add it at the base too.
增加阴影的颜色，一个接近灰色的紫色。然后在明暗交界处增加较深的桔红色/红色。同样的，通常，在高处云会比较的亮，所以在底部也增加一些。


Now the highlight color, a slightly lighter peach. Use the finest brush and squiggle it on wherever there's a left-hand facing edge of the cloud. Again, don't be predictable and regular.
现在轮到高光了，用一个很浅的桃红色。用最细的笔刷曲线在云朵的左边边缘。再次，不要太死板和规则。

Here's a cloud similar to one I saw today, around noon, near the horizon, through my office window. The light is coming not from the side or above, but about 45 degrees or so. This changes where you need to put the highest values; instead of at the edge of each blob of cloud the highest value ends up pretty much centered. So a different technique will be more efficient.
这是个和我今天看见的云朵有点像的，在中午时分，接近地平线，从我的办公室的窗户看到的。光线不是从边上或者顶上来的，而是从大约45度的地方。这改变了你要画最亮的地方的位置；不是在云朵最高的一团，亮部占据了中心部分。所以有点不同的技术会更加有效。


Use a similar ramp to the above, just a bit lighter.
用一个和上面的例子差不多就是亮一点的斜面。
Create a new layer and paint with a sharp edged brush a value slightly lighter and less saturated than the lightest sky color. Darken it a bit at the bottom.
新建一个层，用锐利边缘的笔刷和笔最亮的天空颜色亮一点低饱和度的颜色。在底部加深一点

Turn on 'Preserve Transparency' for the layer and paint full white with the airbrush like this. Vary the brush size quite a lot. The goal is to get this kind of 'cauliflower' look.
用“Preserve Transparency”（保留透明度）的叠加方式，用airbrush像这样画上白色。不断改变笔刷大笑。目的是得到有点像“花椰菜”的样子。

终于让我翻译完了~~翻得不好~水平有限，请原谅~但愿能对你有所帮助~~

仔细看了楼上朋友翻译的文字，感觉这个教程还是技术性的多技巧性的少，作者缺少绘画功力的话还是画不出来，郁闷。。。