Musical scales provide an interesting way to change the emotional content of a piece. To explore this a bit, I'll come up with a few small ideas, and play them in different scales to see how they change.

I'll start with some imagery, which can guide the choice of musical features like rhythm, tempo, scale, or tonality.

Take the Grand Canyon at sunrise. It's silent and vast. A piece with a slow tempo and a noticeable echo might go well with this image. Here's what I came up with after noodling on my guitar for a minute and adding some echo in Audacity.

What about a basketball game in full swing? I'll try a fast tempo.

A bird suddenly taking flight? That could use something slow, following by a flurry of fast, high-pitched, chirpy notes.

Now for the interesting part: playing each idea in different scales.

The two tables below show definitions for several scales and modes, based on how they differ from the major and natural minor scales.

The first scale of the first table should be read as follows:
The Lydian mode, apart from its fourth note, contains all the same notes as the major scale. This fourth note is sharp when compared to the major scale.

Scale Name 1 2 3 4 5 6 7 8
Lydian #
Mixolydian b
Natural minor b b b

Here are a few more scales, but this time defined relative to the natural minor scale.

This time, you'd read the table like this:
The Dorian mode, apart from its sixth note, contains the same notes as the natural minor scale. This sixth note is sharp when compared to the natural minor scale.

Name 1 2 3 4 5 6 7 8
Dorian #
Phrygian b
Locrian b b
Harmonic minor #
Melodic minor (ascending) # #

Now I'll use these scales to create variations of the ideas I started with.

First, I'll play around with the canyon-based melody. It's in E natural minor, and the notes played are the 8th, 7th, 3rd, and 2nd of the scale. I'll try that same pattern 8,7,3,2 in a few other scales.

The basketball game melody is in A natural minor, with the pattern 7,7,7,8,5,3,3,5,8,2*,8. The "*" indicates that the note is in the next-highest octave. You can see how this melody sounds when played in each scale.

Finally, the bird melody is in E natural minor. It starts with an A minor 7th chord, and is followed by the note sequence 7,7,5,7,7,5,7,8.

These are just a few of the many scales available, any of which might be used to create melodies with all sorts of different emotional textures.