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Leaves

5/26/2017

As summer approaches, the once dormant bushes and trees start to grow their leaves again. Leaves are important because they are the plant’s main source of nutrition! A leaf can turn sunlight into glucose through a process called photosynthesis, which is used by the plant for energy.

Function of Leaves

In a plant cell, there is a structure (called the chloroplast) that contains chlorophyll, a pigment that makes the leaves green. When the leaves absorb sunlight and carbon dioxide, chlorophyll converts it into energy to be used by the plant, a process called photosynthesis.

A waste product of photosynthesis is oxygen, which we need to live! While talking to plants won’t make them grow faster, this old wives tale is based on the fact that we exhale carbon dioxide, which is the compound plants need in order to thrive.

Aside from helping plants, leaves also help humans by keeping you cool on hot days by making shade. The leaves fill in the spaces between the branches to make a canopy--sort of like an umbrella--over the tree. Leaves also help make trees good homes for animals, like birds, squirrels, and bugs, by providing them shelter, a place to hide, and even food! The shape of a leaf will also allow you to identify the plant to see if it’s safe to eat or not.

Anatomy and Shapes of Leaves

The body of a leaf consists of a flattened portion, called the blade, that is attached to the plant by a structure called the petiole.

Some leaves don’t have a petiole as the blade expands itself directly from the stem of the plant. These are called sessile leaves, shown in the picture below.

Sometimes leaves are divided into two or more sections called leaflets. Leaves with a single undivided blade are called simple, those with two or more leaflets are called compound.

Here is an image that will help you identify leaves based on their morphology:

Pressing and Framing Leaves

If you’ve found and collected some interesting leaves, you may want to preserve them or put them on display. In this activity, you’ll learn how to press leaves with wax paper so you can keep them for a long time!

You’ll need:
-Leaves
-Wax paper
-A thin towel or paper
-An iron and and ironing board

Step One: place a leaf between two pieces of wax paper, and put a towel/piece of thick paper over the wax.

Step Two: press on the towel or paper with a warm iron to seal the wax sheets together. Take care not to burn yourself and get an adult’s help if needed. This takes about 2-5 minutes on each side, depending on how moist the leaf is. Once you have finished one side, flip the leaf over and do the other side.

Step Three: cut around the leaf, leaving a small margin of wax paper to ensure that it will stay sealed. If you don’t want to cut out the leaves, you can try to peel the wax paper off the leaves, leaving a coat of wax behind to protect the leaves. Try this on one leaf first to see if this method works for you.

If you want to frame the leaves, you can place a few dots of glue on the underside of your pressed leaf and secure it to a piece of paper that will fit inside a frame of your choice. Let the glue dry for about 20 minutes before you put the frame together. Now you can keep many interesting leaves for a long time, and even display them on a wall!

Examples of some common leaves you may find:

Image Credits:

Stachowiak, Kai. “Leaves”. Released into the public domain. Uploaded on 5/20/17 from publicdomainpictures.net

Nyren, Erin (2013). “Photosynthesis”. Property of Discovery Express Kids, LLC.

Nyren, Erin (2017). “Blade and Petiole”. Property of Discovery Express Kids, LLC.

Superior National Forest. “Trillium Cernuum”. Released into the public domain. Uploaded on 5/20/17 from commons.wikimedia.org

Nyren, Erin (2017). “Simple vs. Compound Leaves”. Property of Discovery Express Kids, LLC.

“Leaf Morphology”. Released into the public domain under the GNU Free Documentation License. Uploaded on 5/21/17 from commons.wikimedia.org

Kratochvil, Petr. “Red Oak Leaf”. Released into the public domain. Uploaded on 5/21/17 from publicdomainpictures.net

Kaufman, Sidney (2017). "Bush Leaves".

Hodan, George. "Summer Leaf". Released into the public domain. Uploaded on 5/26/17 from publicdomainpictures.net

Kratochvil, Petr. "Autumn Leaf". Released into the public domain. Uploaded on 5/26/17 from publicdomainpictures.net

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All About Clouds

5/17/2017

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Nearly every day you can look up to the sky and see at least one cloud floating around. Clouds come in all shapes and sizes, and can be thin and wispy or dark and heavy with rain. But at their core, all clouds are made of the same basic molecule: water vapor!

How Clouds Form

During the water cycle, water is evaporated from the surface of the earth as water vapor and condenses into tiny water droplets in the sky that we see as clouds. However, the water vapor needs a non-gaseous surface to stick to when it condenses into droplets, a process called heterogeneous nucleation. During this process, miniscule particles in the air (often in the form of dust or soot) provide a surface that water vapor can condense on, allowing clouds to form. We refer to these particles as condensation nuclei.

Sometimes you can speed up the natural process of cloud formation by adding artificial condensation nuclei; this process is called cloud seeding. Why would you want to accelerate the formation of clouds? It’s a form of weather modification; something people do to either increase the amount of precipitation or suppress hail and fog. Cloud seeding in the United States is used in areas of drought and to prevent too much fog around airports.

Types of Clouds

This is an example of what cirrus clouds look like!

There are ten basic cloud types that can be separated into three categories: high clouds, mid clouds, and low clouds. The high clouds category is composed of cirrus, cirrostratus, and cirrocumulus clouds that form high in the sky. These clouds all have the appearance of being wispy like hair, and can often let the sun or moon shine through them. Cirrus clouds are detached and almost always made up of ice crystals. Cirrostratus clouds form a sheet over most of the visible sky. And cirrocumulus clouds are like a mixture of the other two: detached and sheet-like at the same time.

Mid clouds appear blue or grey, and take up the middle level of the sky. Altostratus clouds are sheets or layers of darker clouds that take up most or all of the sky. Altocumulus clouds have “rolls” or ridges and often occur in conjunction with other cloud types. Nimbostratus clouds are what we refer to as rain clouds. It forms from multiple layers of the altostratus cloud coming together. As precipitation continues, the nimbostratus cloud moves into the low level of clouds.

The lowest level of clouds are those that appear closest to the Earth’s surface, and are often very dense. Cumulus clouds develop vertically in the form of rising mounds or towers that resemble the head of a cauliflower! Stratus clouds are dark and heavy, and if they’re dense enough they can produce drizzle or snow grains. Stratocumulus clouds are grey or white and form in patches that resemble honeycombs! Last but not least, we have the mighty thunderstorm cloud: the cumulonimbus. This cloud looks like a mountain with a smoother top and a dark base that produces precipitation. Cumulonimbus clouds can also produce tornadoes.

Cumulonimbus clouds look pretty fluffy!

Make Your Own Cloud in a Jar

In order to make your own cloud in a jar, we know we need warm water to cool, and some sort of condensation nuclei. It’s best to try this out with another person to help. Here’s what you’ll need for this activity:

A glass jar
Hot water
Ice cubes
A few matches (the smoke will be our condensation nuclei)

First, pour some hot water into the jar, about ⅓ of the volume. Then, have one person light a match while the other prepares to quickly put the lid on. As soon as the match is lit, hold the flame inside the mouth of the jar over the water for a few seconds.

Blow out the match, keeping some smoke on the inside of the jar. The second person will then quickly replace the jar’s lid and put a few ice cubes on top. Now you can watch as a cloud forms in your jar!

For further reference, here’s a YouTube video made by Dr. E showing how to make a cloud in a jar!

References:

“Ten Basic Cloud Types” The National Weather Service, National Oceanic and Atmospheric Administration. http://www.srh.noaa.gov/jetstream/clouds/cloudwise/types.html

Nyren-Erickson, Erin. “How to Make a Cloud in a Jar”. YouTube, uploaded on 9/26/2016. https://www.youtube.com/watch?v=ODCjZQUxCGw

Image credits:

Lee, Alix. “Cloud Sea Panorama”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Carlson, Ronald. “Cloud Texture”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Greyling, Lynn. “Layered Cumulus Cloud”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Rabe, Foto. “Burning Matchstick Fire”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

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Crystallization and Geodes

5/10/2017

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All around the world, snow is slowly melting away and taking one of nature’s most prominent examples of crystalline structures. Ice crystals form in the clouds when extremely cold water droplets freeze onto tiny particles of dust. When that crystal falls to the ground, more water vapor freezes onto the ice and makes even smaller crystals that form the six “arms” of a snowflake! Once snowflakes meet the frozen surface of an object (such as a leaf), the crystals stick together and form a layer of ice crystals called frost. Though the snow may be almost gone, another type of crystal still remains: minerals!

Mineral Crystals and How They Form

The process of forming crystals is called crystallization. This happens when liquids start to cool and harden. The molecules gather together by way of electric attraction and arrange themselves in repeating patterns as they attempt to stabilize as a solid.

Crystallization happens in naturally when liquid rock, called magma, cools slowly. Different minerals in magma crystallize at specific temperatures, which separates them into their own distinct crystals. Many valuable crystals, such as diamonds, rubies, and emeralds form this way. If there are gas bubbles in the magma, crystallization can occur in the form of geodes, which we’ll look into later.

Crystals can also form when water evaporates from a mixture and the solid left behind forms a crystalline structure. Salt crystals (NaCl) often form when the salt water evaporates. This is also how some “rock candy” is made! When a stick or piece of string is left in a saturated solution of sugar water, the sugar molecules will form crystals on the stick/string as the water evaporates.

Crystals have many unique properties! They can have extremely flat surfaces, called facets, that help make up the geometric shape of the crystal. One interesting property that most transparent crystals have is the birefringence property. This creates a double image when one looks through the crystal, almost like a kaleidoscope! There are seven basic crystal shapes, also called lattices: cubic, trigonal, triclinic, orthorhombic, hexagonal, tetragonal, and monoclinic. The shape a crystal takes depends on the type of molecule/atom that makes up the crystal. For example, pyrite (fool’s gold) often forms cubic crystals!

Natural and Homemade Geodes

Most geodes start out as hollow bubbles of gas inside molten rock, but sometimes they can form from the hollow remains of an animal’s burrow or even tree roots! As rain pelts down on a hot bubble of rock, the chemicals in the rock are slowly released into the water. Some of the water soaks through the hard, rocky outside of the bubble and is trapped for a moment on the inside. As the mineral-rich water moves on through the bubble, tiny crystals are left behind, clinging to the sides of the bubble. Millions of years can pass while this flow of water gradually builds more crystals inside the empty space. The crystal formations might become large single crystals or tightly packed micro-crystals, so small that you can’t even distinguish one from another.

Using household materials, we can create our own geodes relatively easily! Here’s what you’ll need:

An egg
A pushpin
Scissors
Liquid glue
A paintbrush
1 cup alum powder
2 cups of water
Any color of food coloring

Step One: Carefully wash the outside of the egg you’ll be using to create the geode. Once it’s clean and dry, carefully poke two holes in the shell, one at each rounded end. Use your mouth to blow into one of the holes and push out the insides of the egg.

Step Two: Once the eggshell is empty, cut it in half (lengthwise) using the scissors. Carefully wash the inside of the shell halves with warm water and wipe them dry with a paper towel. Get the inside surface of the shell as clean and dry as possible without cracking it. Peel off and throw away small pieces of shell from around its edge.

Step Three: Drip some glue on the inside of the shell - it’s okay if some gets on the outside too! Use the paintbrush to spread the glue all over the inside of the shell. Completely cover the interior surface with glue all the way up to, and including, the edges. Use more glue if needed.

Step Four: Sprinkle a lot of alum powder on the inside of the shell. Turn the shell-half over and gently tap out any excess alum. Place it on a paper towel or paper plate to dry overnight.

Step Five: The next day, bring 2 cups of water nearly to a boil and pour it into a bowl. Dissolve 30-40 drops of food coloring into the water. Use any color or color combination you wish. Stir it well!

Step Six: Dissolve ¾ cup of alum powder in the hot water and stir well. Let it sit and cool for about 30 minutes.

Step Seven: Once the water has cooled, place the egg shells in the bowl, alum side up. Gently push them to the bottom of the solution with the spoon and allow them to sit there for 12-15 hours. After 12-15 hours, alum crystals have grown! Carefully remove the shells and place them on a paper towel to dry and finish the geode-creation process. Perhaps you can leave them in the bowl longer and see if they grow bigger!

To investigate this further, check out this website!

Image Credits:

Bentley, Wilson. “Snowflakes”. Released into the public domain. Uploaded on 4/27/17 from commons.wikimedia.org

Kratochvil, Petr. “Frost on Leaves”. Released into the public domain. Uploaded on 4/27/17 from publicdomainpictures.net

United States Geological Survey. “Rough Diamond”. Released into the public domain. Uploaded on 4/27/17 from commons.wikimedia.org

“Macle of Three-Crystal Pyrite”. Released into the public domain. Uploaded on 4/27/17 from commons.wikimedia.org

Denyer, Circe. “Amethyst Geode”. Released into the public domain. Uploaded on 4/27/17 from publicdomainpictures.net

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