Added cloud feedback section

notebooks/foundations/energy-balance-model.ipynb

@@ -95,21 +95,37 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Your first content section"
+    "## 4. Cloud Feedback"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "This is where you begin your first section of material, loosely tied to your objectives stated up front. Tie together your notebook as a narrative, with interspersed Markdown text, images, and more as necessary,"
+    "The cloud feedback mechanism is the most complex feedback discussed in this tutorial. This is because clouds interact with both shortwave (SW) and longwave (LW) radiation and exert varying radiative effects depending on their properties (cloud type, height, optical depth, liquid and ice water content, particule sizes, etc)."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "![High cloud versus low cloud radiative effects](../images/2-whycloudsare.jpg)<br>\n",
+    "[Credit: Paulo Ceppi](https://phys.org/news/2020-09-clouds-piece-climate-puzzle.html)"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Hello world!\n"
+     ]
+    }
+   ],
    "source": [
     "# as well as any and all of your code cells\n",
     "print(\"Hello world!\")"