Science: Pressure, Density, and Temperature PDF

# Pressure, Density, and Temperature ## Conditions of Air The Earth's surface creates four different types of air masses: - **Continental**: Means Dry - **Maritime**: Means Humid - **Polar**: Means Cooler - **Tropical**: Means Warmer ## Air Pressure Air at the bottom of the atmosphere is not al...

# Pressure, Density, and Temperature ## Conditions of Air The Earth's surface creates four different types of air masses: - **Continental**: Means Dry - **Maritime**: Means Humid - **Polar**: Means Cooler - **Tropical**: Means Warmer ## Air Pressure Air at the bottom of the atmosphere is not all the same pressure due to the unequal heating of the Earth's surface. * This unequal heating is caused by the curvature of the Earth and the difference in the specific heats of land and water. ## Wind The differences in air pressure at the surface create wind as air masses with high air pressure move towards areas with low pressure. * **Convection Current:** Warmer, less dense air ascends, creating an area of low pressure. * At the top, air cools, grows denser, and descends, creating an area of high pressure. ## Coriolis Effect The Coriolis effect is the way that moving objects appear to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. ### Winds at the Top of the Troposphere Winds at the top of the troposphere are deflected to the right due to the Coriolis effect. ### Winds at the Earth's Surface Winds at the Earth's surface are deflected to the right due to the Coriolis effect. ## Pressure Systems ### High Pressure Systems In a high pressure system, air descends, creating clear and dry weather. Highs rotate clockwise. ### Low Pressure Systems In low pressure systems, air ascends, taking water vapor up to a cooler altitude and producing condensation and precipitation. ## Tropical Lows Tropical lows are created by patches of warm ocean water. The Coriolis effect makes the low pressure system rotate. If the wind speeds reach 74 m.p.h., the low is considered to be a hurricane. ### Hurricanes In a hurricane, the eye is a calm center surrounded by a wall of ascending warm air. Cooler air from every direction is drawn to the center, bending to the right and creating a counter-clockwise rotation. High winds, massive amounts of rain, and storm surge caused by the storm's low pressure make hurricanes deadly. Like all Tropical Lows, when hurricanes run out of hot ocean water, they dissipate. ## Mid-Latitude Lows Lows that form in the mid-latitudes are usually caused by fronts. ## Fronts A front is a boundary separating air masses. ### Stationary Fronts Stationary fronts are when air masses move side ways and produce cloudy/gloomy weather. ### Warm Fronts Warm fronts are when warm air slowly moves and produces steady rain. ### Cold Fronts Cold fronts are when cold air moves fast and produces storms. ### Occluded Fronts Occluded fronts happen when warm air is trapped above the ground. ## Cumulonimbus Clouds Cumulonimbus clouds are formed by soaring updrafts. * **Downdraft:** Cold air. * **Updraft:** Warm air. Usually, upper level winds blow in a direction similar to the direction of the front. If upper level winds blow in a different direction and at a different speed, the air between upper and lower levels will swirl. A strong updraft can cause the swirling winds to turn sideways. The rotating updraft creates a supercell. * **Forward Flank Downdraft:** * **Rear Flank Downdraft:** * **RFD:** If RFD "hooks" = tornado.