West Facing Slopes

West-facing slopes

Bats can fly extremely high and fast.

In early 2021, the scientist Teague O'Mara and his colleagues published research demonstrating that European free-tail bats in Portugal rise rapidly to heights of nearly one mile, achieving speeds of up to 84 mph. By combining regional wind data with information from GPS trackers carried by the bats, they discovered that bats use orographic lift from prevailing night-time winds that travel up west and south-facing slopes. Basically, they travel up and down the sides of steep hills like a "rollercoaster" with the wind beneath their wings.

The researchers were surprised to discover just how predictable the bats' high-flying ascents were across the landscape. The data show that bats are using the same types of places—although not necessarily always the exact same locations—where the wind sweeps up a slope to carry them to high altitudes.

Most bats descended quickly after reaching their peak elevation, resulting in a kind of rollercoaster flight path.

 Science Tech Daily February 2021

Although it is still unclear how bats use their intelligence to map west and south-facing slopes, humans do it using aspect-slope maps such as this one, which provides a key as an example of how they are created.

Aspect map created by Jay Guernari

West Facing Slopes is one of three based on the harmony and melody in Eddie Vedder's song Rise. It contains some of Vedder's lyrics, along with excerpts from Percy Shelley's Ode to the West Wind.

Listen to Rise

Lyrics to Rise
by Eddie Vedder

Such is the way of the world
You can never know
Just where to put all your faith
And how will it grow

Gonna rise up
Burning black holes in dark memories
Gonna rise up
Turning mistakes into gold

Such is the passage of time
Too fast to fold
And suddenly swallowed by signs
Low and behold

Gonna rise up
Find my direction magnetically
Gonna rise up
Throw down my ace in the hole

 Ode to the West Wind
By Percy Bysshe Shelley
I
O wild West Wind, thou breath of Autumn's being,
Thou, from whose unseen presence the leaves dead
Are driven, like ghosts from an enchanter fleeing,

Yellow, and black, and pale, and hectic red,
Pestilence-stricken multitudes: O thou,
Who chariotest to their dark wintry bed

The winged seeds, where they lie cold and low,
Each like a corpse within its grave, until
Thine azure sister of the Spring shall blow

Her clarion o'er the dreaming earth, and fill
(Driving sweet buds like flocks to feed in air)
With living hues and odours plain and hill:

Wild Spirit, which art moving everywhere;
Destroyer and preserver; hear, oh hear!

II
Thou on whose stream, mid the steep sky's commotion,
Loose clouds like earth's decaying leaves are shed,
Shook from the tangled boughs of Heaven and Ocean,

Angels of rain and lightning: there are spread
On the blue surface of thine aëry surge,
Like the bright hair uplifted from the head

Of some fierce Maenad, even from the dim verge
Of the horizon to the zenith's height,
The locks of the approaching storm. Thou dirge

Of the dying year, to which this closing night
Will be the dome of a vast sepulchre,
Vaulted with all thy congregated might

Of vapours, from whose solid atmosphere
Black rain, and fire, and hail will burst: oh hear!

III
Thou who didst waken from his summer dreams
The blue Mediterranean, where he lay,
Lull'd by the coil of his crystalline streams,

Beside a pumice isle in Baiae's bay,
And saw in sleep old palaces and towers
Quivering within the wave's intenser day,

All overgrown with azure moss and flowers
So sweet, the sense faints picturing them! Thou
For whose path the Atlantic's level powers

Cleave themselves into chasms, while far below
The sea-blooms and the oozy woods which wear
The sapless foliage of the ocean, know

Thy voice, and suddenly grow gray with fear,
And tremble and despoil themselves: oh hear!

IV
If I were a dead leaf thou mightest bear;
If I were a swift cloud to fly with thee;
A wave to pant beneath thy power, and share

The impulse of thy strength, only less free
Than thou, O uncontrollable! If even
I were as in my boyhood, and could be

The comrade of thy wanderings over Heaven,
As then, when to outstrip thy skiey speed
Scarce seem'd a vision; I would ne'er have striven

As thus with thee in prayer in my sore need.
Oh, lift me as a wave, a leaf, a cloud!
I fall upon the thorns of life! I bleed!

A heavy weight of hours has chain'd and bow'd
One too like thee: tameless, and swift, and proud.

V
Make me thy lyre, even as the forest is:
What if my leaves are falling like its own!
The tumult of thy mighty harmonies

Will take from both a deep, autumnal tone,
Sweet though in sadness. Be thou, Spirit fierce,
My spirit! Be thou me, impetuous one!

Drive my dead thoughts over the universe
Like wither'd leaves to quicken a new birth!
And, by the incantation of this verse,

Scatter, as from an unextinguish'd hearth
Ashes and sparks, my words among mankind!
Be through my lips to unawaken'd earth

The trumpet of a prophecy! O Wind,
If Winter comes, can Spring be far behind?

Image credit - Jay Guarneri's aspect map used with permission
Image credit - Public Domain Rain shadow and orographic lift