Informational Booklet By: Emma and Aakriti
Atmosphere The atmosphere is composed of four layers. The troposphere is the bottom layer and is the closest to the earth. Above it lays the stratosphere, this layer contains the ozone layer and protects us from the harmful rays of the sun. The next layer is the mesosphere. The outermost layer is called the thermosphere, but is also known as the ionosphere. In the thermosphere most small meteorites burn up. It is also where aurora borealis (the northern lights) occur. The atmosphere is made from the combination of many different types of gases, including nitrogen, oxygen, argon, carbon dioxide, and other noble gases. As 78.03% of the volume of the atmosphere, nitrogen is the most abundant. Oxygen makes up about 20.99% of the atmosphere, the rest of the noble gases make up the remaining 0.08% of the atmosphere.
Convection Convection is the transfer of heat by the movement of a liquid or gas. Convection currents can show up in the atmosphere, the ocean, or even the earth's mantle.
Wind Currents Wind is caused by difference in the pressure of the air. Local winds: Local winds are caused by unequal heating of the earth's surface. Local winds blow over short distances, unlike Global winds, which blow over longer distances. The Coriolis Effect: The Coriolis Effect is when the earth's rotation causes air and water that's moving to change it's direction. There are four types of global winds: Doldrums, Trade winds, Prevailing Westerlies, and Polar Easterlies. Doldrums ~ These are located near the equator, they're calm and weak winds. Trade Winds ~ Located just north and south of the equator, there are very few clouds and rain. Prevailing Westerlies ~ These winds are strong, located around/above the Trade Winds. They also have an impact on the US. Polar Easterlies ~ Though they are very cold, these are also weak, and located near the north and south poles.
Ocean currents Surface currents: Surface currents are like rivers moving through the ocean. They can go as deep as several hundred meters, and are driven by wind. Currents above the equator move in a clockwise motion, currents below the equator move the opposite way. Gulfstream: The Gulf Stream is in the North Atlantic Ocean, and was found by Ponce de Leon in the 1500's. Most known info about currents was found in the Gulf Stream. Density currents: Density currents are made where seawater sinks under colder water. They are found deep in the ocean where there is no wind. They act like a conveyer belt, the colder water on the top, and the warmer water on the top.
High Pressure High Pressure, often represented with a blue letter H, is also known as an anticyclone. The motion of the air in a high pressure area moves clockwise, and causes a zone of divergence. Weather that is brought with high pressure is usually steady and calm.
Low Pressure Low Pressure, often represented with a red letter L, is also known as a cyclone. The motion of the air in a low pressure area is the opposite of a in a high pressure area, moving counterclockwise. The weather is not as stable as with high pressure, usually cloudy and changeable, with precipitation.
Fronts There are four types of fronts: Cold fronts, Warm fronts, Stationary fronts, and Occluded fronts. Cold Fronts ~ Cold fronts happen when a fast moving cold air mass runs into a slow warm air mass, and the cold air slides under the warm air. The warm air is pushed up by the cold air, creating a cold front. Cold fronts move very quick, and cause fast changes in the weather. Cold fronts usually bring clear skies and cold temperatures. Warm Fronts ~ Warm fronts are created when a moving cold air mass hits a slow cold air mass, and just like in a cold front, the warm air goes above the cold air. Warm fronts are slower than cold fronts, and bring warm weather in the summer, and snow in the winter. Stationary Fronts ~ Stationary fronts are when warm and cold air masses meet, but neither have the power to move the other. If the front is slowed, there may be days of clouds and rain. Occluded Fronts ~ Occluded fronts are the most complicated fronts, and happen when a mass of warm air is caught between two masses of cold air. The warm air mass is cut off from the ground, and the ground temperature gets colder. The weather can turn cloudy, with rain or snow.
Hurricanes Hurricanes are tropical storms with very high wind speeds. Hurricanes are formed over warm water as either a area with low pressure, or a tropical disturbance. When the disturbance grows, it becomes a hurricane. A hurricane gets it's energy from warm air at the surface of the ocean. The center of the hurricane is called the "eye of the hurricane," and is the calmest part of the hurricane. Hurricanes last longer than normal storms, usually a week or more. Hurricanes formed in the Atlantic ocean are usually steered towards the caribbean islands or southeastern United States, by easterly trade winds.
Tornados Tornadoes are clouds which are funnel shaped and whirl rapidly. They can reach wind speeds of up to 300 mph. They reach down and touch the Earth's surface from storm clouds. When a warm and cool air masses meet, they cause thunderstorms and make the atmosphere unstable. An invisible, horizontal, spinning effect is created in the lower atmosphere by the changing wind direction and an increasing wind speed. Rising air changes this spinning to go from horizontal to vertical. Tornadoes leave behind mass destruction in the paths.
Sun and it's energy Nearly all of the Earth's energy comes from the Sun. The energy travels to earth in the form of electromagnetic waves. These waves are classified by their length. The waves can be visible, infrared, or ultraviolet. Some of the energy coming from the Sun is absorbed into the atmosphere. Water and carbon dioxide absorb some infrared radiation. The ozone absorbs some ultraviolet radiation. Clouds, dusts, and other gases in the atmosphere also reflect some energy back into space. Some of the energy is absorbed into the surface of the Earth, heating up the land and water. Some energy is scattered, when the light is reflected in all directions. Gas molecules scatter short wavelength light, which is blue, towards the sky. This is what makes the sky look blue.
Weather Maps Meteorologists make weather maps from information that they gather using their various weather instruments. There are six basic types of weather maps; Satellite, Radar, Precipitation, Temperature, Wind Speed, and Front. Symbols can be used to represented for information such as Air Pressure, High and Low Pressure, Wind, Wind Direction and Velocity, Fronts, Various Precipitation, and Temperature.
Isotherm and Isobar Isotherms are lines which represent equal temperature.
Isobars are lines of equal pressure on a weather map. The closer two isobar lines are, the stronger the pressure.
Types of precipitation There are four different types of precipitation; Rain, Snow, Sleet, and Hail. Precipitation occurs when there is a large buildup of water vapor in a small portion of the atmosphere, the water vapor gets so condensed and it precipitates. Which form it precipitates in depends upon the local weather. Rain is the most common type of precipitation, it comes down in two main forms; drizzles and showers. Showers are periodic and don't last a very long time. They are much heavier than drizzles, which are more consistent and longer. Snow is formed when water vapor is turned to ice without passing through a liquid state. Sleet is formed when the water vapor does pass through a liquid state between water vapor and freezing, it usually comes as a combination of snow, rain, and frozen rain. Ice crystals are formed inside cumulonimbus clouds. As they fall down, they begin to grow in size. This is because they are caught by powerful winds and pushed back up, and every time they fall, they accumulate more moisture. When the ice crystals get too big for the wind to push them back up, they fall to earth in the form of hail.
Types of clouds There are four basic types of clouds; Cumulus, Stratus, Cirrus, and Nimbus. There are many more combination clouds that can be formed from these. Cumulus clouds are fluffy, white clouds that look like cotton and are less than 2 km above the surface. Stratus clouds form in flat layers. Cirrus clouds are wispy and feathery made up mostly of ice crystals, about 6 km above the surface. Nimbus clouds are dark and gray and hold rain inside of them.
Dew Point Dew point is the temperature at which condensation (water vapor changing into a liquid--or solid--state of matter) begins. Water vapor may directly change into ice crystals if the dew point is below freezing. At a normal dew point, tiny water droplets are formed. Dew forms on on solid surfaces where condensation has occurred.
How Scientists Get Images Scientists use satellites to get images. Satellites can take pictures from space, and help scientists predict storms.
Meteorological Instruments There are many different instruments that meteorologists use to measure and study weather. An anemometer measures wind speed. There are mercury barometers and aneroid barometers, both are used to measure changes in air pressure. A psychrometer is used to measure relative humidity. A rain gauge is used to measure rainfall. Weather balloons are used to carry packages of instruments high into the atmosphere to measure weather conditions. Weather satellites send frequent images of the earth, with their infrared and visible cameras, providing views of storms and monitoring the weather from above.