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Predicting the Weather. Thermometer. Used to measure temperature Units Fahrenheit (°F) Celsius (°C) Kelvin (K). Wind. Anemometer. Vane. Measures wind DIRECTION. Measures wind SPEED . . Air Pressure. Barometer Two types Mercury Aneroid. Doppler Radar.
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Thermometer • Used to measure temperature • Units • Fahrenheit (°F) • Celsius (°C) • Kelvin (K)
Wind Anemometer Vane Measures wind DIRECTION • Measures wind SPEED.
Air Pressure • Barometer • Two types • Mercury • Aneroid
Doppler Radar • Uses the Doppler effect (change in wave frequency) to plot the speed at which raindrops move toward or away from a radar station
Weather Station ModelsA record of weather data for a particular site at a particular time.
Thunderstorms • Recipe: • Unstable air • Convection • Conduction • What is unstable air? • To be "unstable", the lowest layers of an air mass must be so warm and/or humid that, if some of the air rises, then that air parcel is warmer than its environment, and so it continues to rise. This is called moist convection.
Three Types: Frontal thunderstorms occur along the boundaries of weather fronts (e.g. cold front). Orographic thunderstorms are caused by air that is forced up by a mountain or hillside. Air mass thunderstorms are the result of localized convection in an unstable air mass.
Lightening Lightning happens when the negative charges in the bottom of the cloud are attracted to the positive charges in the ground. A stream of negative charges pours down towards a high point where positive charges have clustered due to the pull of the thunderhead. The connection is made and the protons rush up to meet the electrons.
Thunder • Lighting heats the surrounding air to about 30,000⁰ C • “Explosion of Air” • Light waves travel faster than sound waves
Tornadoes!!! • Violently rotating column of air in contact with the ground • Rotating updraft is a key to the development tornado. • Caused by wind shear
Hurricanes • Tropical cyclones with winds that exceed (74 mi/hr) • circulate counter-clockwise Northern Hemisphere • Clockwise in the Southern Hemisphere • Water must be warmer than 81 F
A tropical depression is designated when the first appearance of a lowered pressure and organized circulation in the center of the thunderstorm complex occurs Avg. wind speeds ~ 38 mph Stages of DevelopmentDepression Storm Hurricanes
Tropical StormA powerful storm that begins in the tropics; has winds which are not as strong as those of a hurricane • Do not have a well defined eye. • Avg. speeds range ~ 39 mph- 73 mph
Factors to Consider….. El Nino La Nina A cooling of the ocean surface off the western coast of South America, occurring periodically affecting Pacific and other weather patterns. • Above average Pacific Ocean sea surface temperatures and atmospheric conditions that change the places where storms go