Choppers are mainly designed to fly short distances and typically fly much lower than airplanes, normally at under 10, feet. They are also unable to ascend to the same height an airplane can because instead of wings, helicopters fly by rotating blades. Birds are most likely to obstruct planes at lower altitudes, and can present problems during takeoff and landing. The extreme case of that would be the U. But when planes are at cruising altitude, experts say birds are no longer a threat.
So once the seatbelt signs goes off, you can relax and enjoy the flight. Contact us at letters time. By Celine Hacobian. Related Stories. Here's What Travel Experts Say.
America Needs to Get Back to Facts. The next higher layer above the stratosphere is the mesosphere.
The bottom of the stratosphere is around 10 km 6. The top of the stratosphere occurs at an altitude of 50 km 31 miles. The height of the bottom of the stratosphere varies with latitude and with the seasons. The lower boundary of the stratosphere can be as high as 20 km 12 miles or 65, feet near the equator and as low as 7 km 4 miles or 23, feet at the poles in winter. The lower boundary of the stratosphere is called the tropopause; the upper boundary is called the stratopause.
Ozone, an unusual type of oxygen molecule that is relatively abundant in the stratosphere, heats this layer as it absorbs energy from incoming ultraviolet radiation from the Sun. Temperatures rise as one moves upward through the stratosphere. This is exactly the opposite of the behavior in the troposphere in which we live, where temperatures drop with increasing altitude. Because of this temperature stratification, there is little convection and mixing in the stratosphere, so the layers of air there are quite stable.
Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below. The stratosphere is very dry; air there contains little water vapor. Turbulence can also be caused by clear air turbulence, or CAT, which occurs when a strong jet stream is found between mixing regions.
Nevertheless, more often than not, there is little to no bad weather found in the stratosphere, which results in smooth flying for most aircraft. Less turbulence is valuable for many reasons and this is why flying in the stratosphere layer of the atmosphere is the rule for most aircraft.
There is less air friction and an increase in the true airspeed, or TAS, of the airplane, which results in a higher flying speed. Flying faster is especially important in commercial flights because passengers always expect their planes to land and take off at a certain time.
With faster flying speeds, the passengers can count on few or no late flights and are happy that their flights will take off and land when the airline company says they will. It is easy to understand why better winds make for better flights, and this is another one of the many reasons why stratosphere flying is the norm for most aircraft.
Jet streams can increase ground speed and allow a flight to be shorter under certain circumstances. Jet streams move from west to east and the northern hemisphere has three types of jet streams. When the jet stream is pushing an airplane to the east, it is easier for the plane to make good time.
Of course, if a jet stream is blowing as a headwind it can have the opposite effect, which is why most flights are designed to make the most out of jet streams. After all, no one wants extra time added to their flight; only the opposite is ever desired.
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