A) Weather and Climate

What is weather? What is climate? What's the difference? Weather is the day-to-day conditions of a particular place. For example: It was raining today at school. Yesterday it was sunny at home. Every day before school you have to dress differently because it might be cold or warm, or rainy or sunny. This is because of weather. Climate is often spoken about at the same time as weather, but it is something quite different. The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years). We learn about different climates around the world. Deserts have a hot and dry climate while the Antarctic has a very cold and dry climate.

NASA has lots of satellites that study weather and climate. The GOES satellite is an important NASA and NOAA mission that supports weather forecasting, storm tracking, and many other things. The Tropical Rainfall Measuring Mission, or TRMM, is an example of a NASA mission designed to study rainfall and precipitation. TRMM can also be used to study weather and climate conditions around the world. NASA's Aqua satellite also studies weather and played a part in monitoring Hurricane Katrina as well as many other storms. There are all kinds of weather. It can be hot, cold, rainy, windy, cloudy, clear, or humid. More extreme weather conditions create things like storms and hurricanes. A storm is a severe weather event that can be full of wind, rain, lightning, and thunder. Hurricanes and tornadoes are just different names for a powerful, rotating storm with thunder, lightning and rain. Hurricanes are one of the atmospheres most powerful and dangerous forces. They are a major hazard to people, buildings and the environment.

B) Oceans and Ice

What is an ocean? An ocean is a large body of water between continents, such as the Atlantic Ocean and the Pacific Ocean. Oceans cover 70% of the surface of the Earth. Oceans can be very deep, and the deepest ocean is the Pacific Ocean, with its deepest point being about 11,000 meters or 36,000 feet deep. That's deep enough to fit several skyscrapers on top of each other! What is ice and is there ice in the oceans? Ice is simply frozen water, and ice exists in many places in Earth's oceans. Near the north and south poles are huge areas of ice. Antarctica is an entire continent full of ice at the south pole. The Arctic region near the north pole is another massive area full of ice.

There are also large objects called icebergs that float in the oceans near to the north and south poles of the Earth. Why does ice in the oceans matter? Well, you may have heard of global warming, and global warming is causing the ice in the oceans to melt. Global warming is a slow but steady rise in Earth's surface temperature. If too much ice melts in the oceans, then the water level around the world will keep rising in the future, causing floods and affecting millions of people. NASA has several missions designed to study the melting of glaciers and icebergs in the oceans. The SeaWIFS instrument is useful in monitoring ocean characteristics such as water color and clarity. The Aqua mission is a NASA earth science satellite designed to study the Earth's water cycle in its liquid, solid and gas forms. Another example is the recent ICESat mission also designed to study changes in ice around the world.

C) Vegetation and Agriculture

What is vegetation and agriculture? Vegetation and agriculture are the plants, trees, fruit, vegetables, and other things that grow out of the ground. People all over the world depend on the farming and agriculture to eat food and survive. Vegetation is the plant life of a region, it can mean anything from a redwood forest to a field of wheat. It's important to monitor areas of vegetation around the world. Agriculture is a fancy word for farming, forestry, or the growing of crops.

What does NASA have to do with vegetation and agriculture? That's a good question. It's important to see and watch how well plants, trees, and crops are growing all over the world, and the fastest and best way to do that is using satellites that are in orbit around the world. These are called Low Earth Orbit satellites, or LEO's. If an area of crops is growing too slowly or a rainforest is getting smaller, it's very useful to have NASA satellites in orbit to find out this information for us so we can do something about it. One of the functions of the Landsat mission is watching agriculture and vegetation from space and to see how well things are growing. The satellite has a camera device onboard that gathers pictures of the ground. The Terra mission is designed to track carbon in the atmosphere produced by plants and trees. Many NASA missions are designed to study vegetation and agriculture trends around the world.

D) Earthquakes and Volcanos

Let's talk about natural disasters. What are earthquakes? An earthquake is a violent movement of the rocks in the Earth's crust. Earthquakes are usually quite brief, but may repeat over a long period of time. Earthquakes are measured with a seismometer. The magnitude of an earthquake, and the intensity of shaking, is measured on a numerical scale. On the scale, 3 or less is barely noticeable, and magnitude 7 or more causes damage over a wide area.

What are volcanoes? A volcano is a mountain where lava (very hot, molten rock) comes from a magma chamber under the ground. Most volcanoes have a crater at the top. Materials which poured out from it usually include lava, steam, sulfur, ash and rocks. Lava is called magma before it has come out of the volcano. Volcanoes are made when magma and pressure come together and it blasts out of the crater out of the top.

NASA's EO-1 mission was used to monitor Iceland's Eyjafjallajokull volcano eruption in 2010. There are many other natural disasters that occur around the world, such as forest fires, floods, droughts, landslides and many others. Studying and tracking these natural disasters is critical to saving lives around the world. NASA has several missions designed to study earthquakes, volcanoes, and other natural disasters. NASA plays a big part in watching where these disasters take place from orbit and directing help and assistance to the people in those areas.

E) Gravity and the Magnetosphere

Let's talk about two interesting subjects. Gravity, and the Earth's magnetic field. Simply put, gravity is the force that draws an object or living thing downwards. Gravity is the force from the Earth that keeps you and all objects on the ground. Otherwise, we would all just float away into space. If you think about the gravity around the Earth, you may think of it as a sphere, but the Earth's gravity is actually shaped more like a pear. Pretty neat, eh? Now let's talk about the Earth's magnetic field. Let's start with a magnet. A magnet is a special kind of metal that will push or pull other metals away. Now look at a compass, which is used for navigation. The compass will use the Earth's magnetic field to always point North.

You can think of the Earth as a large magnet and it exerts a large magnetic field all around the Earth. This is also called the magnetosphere, and it protects the Earth from dangerous solar wind that is shot at the Earth from the Sun. Good thing it's there!

NASA has several missions designed to study the Earth's gravity and magnetic field. The Magnetospheric Multiscale Mission (MMS) is a NASA mission consisting of four satellites orbiting our planet to study all kinds of particles and different things in the Earth's magnetic field. The Gravity Recovery And Climate Experiment (GRACE), a NASA mission has been making detailed measurements of Earth's gravity field since its launch in 2002. Gravity is determined by mass. By measuring gravity, GRACE shows how mass is distributed around the planet and how it varies over time. GRACE data are important tools for studying Earth's ocean, geology, and climate.

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