2 Weather InstrumentsRain Gauge – measures the amount of precipitation that has fallen in an area.Thermometer – measures temperature in degrees Fahrenheit or Celsius.Weather vane – measures wind direction
3 Weather InstrumentsAnemometer – the cups on the anemometer spin in the wind. The anemometer calculates the wind speed in miles per hour of kilometers per hour.Barometer – measures air pressure in units called millibars.1030 millibars = fair weather
4 Why do we have wind?Air moves from areas of high pressure to low pressure.During the day, the Sun heats up Earth’s surface. Earth’s surface warms up the air. As the air warms it expands (This is low pressure). During the day, cool ocean breezes move toward the land.Oceans change temperature slowly, so they never become as warm as the land. As the warm air above the land begins to expand, the cooler, heavier air moves towards the land. At night, the land cools off quicker causing cool air above the land moves toward the ocean.
5 Let’s look at this map…We know that low pressure means that the air is warm. So high pressure means the air is cold.What do you think will happen in this picture?
6 What are air masses? Polar air mass bring cold air Land air mass brings dry airTropical air mass brings warm airOcean air mass brings wet air.
7 Take a guess? What kind of weather would you get if you had… Tropical land air mass?Polar ocean air mass?Tropical ocean air mass?Polar land air mass?
8 Weather PatternsWeather in North America usually moves from West to East. The weather in Illinois will normally be in New York in two days.Front – The place where two air masses meet.Cold Front -Warm Front -