Adding image alt tag to twig template

Can't find a way to add an alt"" tag based on the imagename to every image. In my template i'm adding the images like this:

{% for image in page.media.images %}
<li>
<div class="image-surround">
{{ image.lightbox(1024,768).cropResize(215,215).html }}
</div>
</li>
{% endfor %}

The .html action accepts an alt tag: see docs