For ads that are placed above-the-fold, it's recommended to use a fixed height layout, like this one:
<amp-ad layout="fixed-height" height="100" type="adsense" data-ad-client="ca-pub-12345678910234" data-ad-slot="1234567890"> </amp-ad>
Following this brief diversion, the sole purpose of which is to ensure that there is enough content so that the next ad will be below-the-fold, we'll see a below-the-fold ad.
We will, in fact, be seeing the below-the-fold ad very soon, very soon indeed. In the meantime, I have an important question for you: What greater gift than the love of a cat?
For below-the-fold ads, it's recommended to use a responsive layout, like this:
<amp-ad layout="responsive" width="300" height="250" type="adsense" data-ad-client="ca-pub-12345678910234" data-ad-slot="1234567890"> </amp-ad>