Severe Weather & Climate Notes

1. Severe Weather & Climate Notes

2. Fronts • When fronts move through an area, the result is usually precipitation and a change in wind direction and temperature. • air mass:a large body of air where temperature and moisture content are similar throughout • front: the boundary between air masses of different densities and usually different temperatures

3. Fronts • Clouds, rain, and sometimes snow can occur at fronts. • Front types include • warm fronts • cold fronts • stationary fronts

4. Thunder & Lightning • Lightning is a discharge of atmospheric electrical energy. • Water droplets and ice crystals in thunderclouds build up electrical charges. • Lightning is a big spark that jumps between clouds or between clouds and Earth to equalize the charge. • Lightning heats the air so fast that the air expands faster than the speed of sound. • The shockwave created is thunder.

5. Severe Weather • Tornadoes are funnels of high-speed wind. • Tornado winds are the most violent winds on Earth. • Wind speeds may reach up to 500 km/h. • Tornadoes typically form along a front between cool, dry air and warm, humid air. • funnel cloud: a column of water droplets

6. Severe Weather • Hurricanes are large, rotating tropical storm systems. • These storms are called • hurricanes in North America and the Caribbean • cyclonesin the Indian Ocean • typhoonsin the western Pacific • tropical depressions: intense low-pressure areas that can become hurricanes

7. Climate • Weather changes from day to day, but climate does not change as quickly. • climate:the average weather conditions in an area over a long period of time. Two main factors are temperature and precipitation.

8. Climate • Temperatures tend to be higher close to the equator. • Sunlight strikes the earth more directly close to the equator. • The sun’s rays are less concentrated at the poles, and do not warm the atmosphere as much.

9. Climate • Earth’s tilt and rotation account for our seasons. • When the North Pole is tilted toward the sun, the Northern Hemisphere experiences summer. • There is more daylight, and the temperature increases. • Earth is farthest from the sun on July 4. • When the South Pole is tilted toward the sun, the Southern Hemisphere experiences summer.

10. Climate • Earth’s surface features affect climate. • topography:the size and shape of the land surface features of a region, including its relief • Variations in topography affect the climate of a region. • Mountains can trap moisture on one side. • Deserts may form on the dry side of a mountain. • Broad flat surfaces allow winds to merge on the plains. • Thunderstorms and tornados may form.

11. Exit Slip • Determine whether each of the following statements describes a warm front or cold front. • Warm air mass moves above slow cold air mass • Thunderstorms and high winds characterize this type of front • Cold air moves quickly under slow air mass • Steady rain • Grapes grow well in areas where climate is generally mild. Would you recommend planting grapes in California or North Dakota? Explain.

12. Climate Change • Global climate changes over long periods of time. • Many factors produce changes in Earth’s climate, such as: • eruptions of volcanoes • shift of the continents • changes in Earth’s tilt • Scientists think that increases in human-made greenhouse gases have caused the recent increase in global average temperature.