Lydian

Lydian is the fourth mode of the major scale. The lydian scale is essentially identical to the major scale, except the 4th is sharp.  

The scale degrees are as follows:

1   2   3   #4   5   6   7

This scale is not as common as the other major sounding scales, but is very useful in creating lofty, wispy melodies. 

Often found in jazzy contexts, this scale is implied whenever you see major chords with a #11 extension.

While you can certainly play this scale over a regular major chord, you will find that hanging on the #4 (11) will clash with the 5th of the chord and create dissonance. 

Therefore, unless dissonance around the fifth is what you are going for, this scale degree is normally used as embellishment in passing to "tease" the fifth and kind of "loft" around the third.

Note: When the lydian scale is used over a IV chord (as it should be, given it is the fourth mode), the #4 is actually the 7th or leading tone of the tonic. Ie: In the key of E major, A lydian contains a D#. 

Therefore, the most obvious time to sound lydian (hang on the #4) in diatonic harmony is when you have a IV chord going to I chord. 

When we build 7th chords off of the lydian scale we are left with the following:

I ma7   II7   III mi7   #IV mi7(b5)   Vma7   VI mi7   VII mi7

Common dorian progressions include:

• IVma - Ima
• Ima7 - II7

Attached are the five patterns of the lydian scale.  Also supplied are jam tracks for the above progressions, along with a I chord vamp.  Again, I want you to use the technique of starting with the major pentatonic scale, then adding in the #4, and then the whole lydian scale. 

Play close attention to the leading tone (#4) when resolving down a fourth. This is a funky sound but it is very fun and whimsical.

Jam Tracks:

1.  D lydian - D vamp

2.  F lydian - IVma - I ma

3.  C lydian - Ima7 - II7